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Acce&sio u  No .     92  3  2  3    >>   Class  No . 


SMOKELESS   POWDER, 
NITRO-CELLULOSE, 


AND 


THEORY  OF  THE  CELLULOSE 
MOLECULE 


BY 


JOHN  B.  BERNADOU, 

Lieutenant,  United  States  Navy 


FIRST  EDITION' 
FIRST     THOUSAND 


NEW    YORK 

JOHN  WILEY    &    SONS 

LONDON  :   CHAPMAN  &  HALL,  LIMITED 

IQOI 


Copyright,  1901, 

BY 
JOHN   B.  BERNADOU 


ROBERT  DRUMMOND,    PRINTER,  NEW  YORK 


PREFACE 


FOR  purposes  of  comparative  study,  the  writer  has 
brought  together  in  the  present  volume  a  series  of 
papers,  by  various  investigators,  upon  the  composition 
of  cellulose  and  the  properties  of  explosives  prepared 
therefrom.  He  has  supplemented  these  with  an  ac- 
count of  experiments  made  by  himself;  and  from  the 
whole  has  drawn  certain  conclusions  as  to  the  possible 
ultimate  chemical  composition  of  cellulose  and  the 
nitro-celluloses. 

While  the  general  development  of  war-material 
from  the  mechanical  and  metallurgical  standpoints — 
the  production  of  ordnance  and  armor — is  so  largely 
identified  with  progress  in  the  useful  arts  in  the 
United  States,  yet,  until  very  recently,  but  little  has 
been  accomplished  in  our  country  in  the  way  of  im- 
provement in  explosives.  Within  the  last  few  years, 
however,  a  particular  form  of  smokeless  powder  has 
largely  supplanted  the  old  black  and  brown  powders 
for  military  uses ;  and  the  last  decade  of  the  past 
century  has  witnessed  the  virtual  abandonment  of 
a  propellant  that  has  held  its  place  in  war,  with 

in 

92323 


IV  PREFA  CE 

comparatively   little   modification,    for   four    hundred 
years. 

This  new  smokeless  powder,  which  is  adapted  for 
use  in  arms  of  all  calibres,  is  prepared  from  a  particu- 
lar type  of  colloid  nitro-cellulose.  Such  an  extension 
of  the  employment  of  this  latter  body  from  its  original 
use  for  detonating  purposes,  to  its  new  use  as  a  pro- 
gressive explosive,  has  attracted  general  attention,  and 
led  to  a  more  careful  and  extended  study  of  the  nitro- 
celluloses  in  general.  It  is  with  the  view  of  further 
extending  such  study  and  of  possibly  preparing  the 
way  for  the  introduction  of  future  improvements  in 
progressive  explosives  that  this  book  has  been  pre- 
pared. 

Before  presenting  it,  the  author  wishes  to.  express 
his  thanks  to  certain  eminent  scientists  for  the  privi- 
lege that  they  have  courteously  afforded  him  of 
making  his  own  translations  of  certain  portions  of  their 
works  upon  explosives :  to  Professor  D.  Mendeleef, 
of  Russia,  for  his  paper  entitled  "  Pyrocollodion 
Smokeless  Powders";  to  M.  Vieille,  of  the  French 
Service  des  Poudres  et  Salpetres,  for  his  article  upon 
the  nitration  of  cotton  ;  and  to  M.  Bruley,  of  the  same 
service,  for  a  similar  paper.  Thanks  are  due  also  to 
Messrs.  Longmans,  Green  &  Co.  for  the  privilege 
kindly  extended  of  making  certain  extracts  from 
Messrs.  Cross  and  Bevan's  valuable  work,  ' '  Cellulose, ' ' 
published  by  them. 

Finally,  the  author  wishes  to  express  his  indebted- 
ness to  Dr.  Alfred  I.  Cohn,  of  New  York,  for  the  care 
he  has  bestowed  upon  the  reading  of  the  proof  of 


PREFA CE  V 

this  book  at  a  time  when  the  writer's  absence  from 
the  United  States  on  active  service  afloat  prevented 
his  giving  the  matter  the  personal  care  and  attention 
it  otherwise  would  have  had ;  and  for  his  prepara- 
tion of  a  comprehensive  index. 

U.  S.  S.  "  Dixie,"  April  24,  1901. 


TABLE  OF  CONTENTS 


CHAPTER  I 

PAGE 

Origin 1 

Nomenclature , 4 

Definitions 5 

CHAPTER  II 

EARLIER  VIEWS  AS  TO  NITROCELLULOSE  COMPOSITION  AND 
CONSTITUTION 8 

CHAPTER  III 

THE  CONCEPTION  OF  PROGRESSION  IN  RELATION  TO  COMPO- 
SITION AND  CONSTITUTION 21 

CHAPTER  IV 

SOLUTIONS  OF  NITRO-CELLULOSE.    THEORY  OF  THE  CELLU- 
LOSE MOLECULE.  . .  38 


APPENDIX  I 

RESEARCHES   UPON   THE   NITRATION   OF    COTTON.     BY  M. 

VIEILLE 81 

I.  First  Method  of  Nitration 81 

II.  Second  Method  of  Nitration 87 

III.  Higher  Limit  of  Degree  of  Nitration 91 

IV.  Cellulose  Incompletely  Nitrated 92 

V.  Resum6  and  Conclusions. .  94 


Vlll  TABLE   OF  CONTENTS 

APPENDIX  II 

PAGE 

PYROCOLLODION   SMOKELESS   POWDERS.     BY  PROFESSOR  D. 
MENDELEEF 97 

APPENDIX  III 

THE  NITRATION  OF  COTTON.    BY  M.  BRULEY 127 

I.  Method  of  NitraCion  and  Mode  of  Representing  Results. .  130 

II.  Results  Obtained  by  M.  Vieille 131 

III.  Experiments  in  Nitration  (First  Series) 134 

IV.  Experiments  in  Nitration  (Second  Series) 140 

V.  Experiments  in  Nitration  (Third  Series) 141 

VI.  Various  Experiments 144 

VII.  Resume  and  Conclusions 152 

APPENDIX  IV 

THE  DEVELOPMENT  OF  SMOKELESS  POWDER.    BY  LIEUTEN- 
ANT JOHN  B.  BERNADOU,  U.  S.  N 156 

INDEX  ..  .  195 


SMOKELESS  POWDER 


CHAPTER  I 
ORIGIN 

THE  discovery  that  cellulose,  by  treatment  with 
nitric  acid,  is  converted  into  a  highly  inflammable  or 
explosive  body  was  made  during  the  first  half  of  the 
nineteenth  century.  The  action  of  nitric  acid  on 
starch  was  investigated  to  some  extent  in  1833  by 
Braconnot,  who  found  that  a  very  rapidly  burning 
material  was  produced,  and  which  he  named  xyloidine. 
Pelouze  further  investigated  this  substance  in  1838, 
and  also  studied  similar  bodies  prepared  from  paper, 
linen,  etc.,  which  he  held  to  be  identical  with  the  one 
from  starch. 

In  1846  Schonbein  discovered  that  cellulose  in  the 
form  of  cotton,  when  immersed  in  nitric  acid,  freed 
from  the  acid  excess,  and  dried,  was  converted  into  a 
highly  explosive  compound.  This  latter  substance, 
subsequently  known  as  gun-cotton,  constitutes  the 
base  of  modern  smokeless  powders.* 

*  The  name  "  gun-cotton,"  as  originally  employed,  was  generic 
for  all  varieties  of  the  more  highly  explosive  nitro-celluloses  pre- 
pared from  cotton. 


2  SMOKELESS  POWDER 

On  its  first  appearance  gun-cotton  was  hailed  by 
ordnance  experts  as  a  smokeless  substitute  for  gun- 
powder, and  extended  series  of  experiments  were  con- 
ducted to  prove  its  adaptability  to  the  requirements  of 
war.  The  combined  efforts  of  chemist,  powder-maker, 
and  artillerist  failed,  however,  to  secure  such  a  control 
of  its  combustion  as  would  enable  it  to  be  safely  em- 
ployed, in  charges  of  a  given  weight,  to  develop  a  uni- 
form bore-pressure  with  standard  projectiles  in  guns  of 
a  given  calibre.  After  the  occurrence  of  a  number  of 
detonations,  unlocked  for  and  more  or  less  disastrous, 
its  use  was  abandoned.  Nevertheless,  the  study  of 
the  composition,  properties,  and  methods  of  production 
of  gun-cotton  and  kindred  bodies  continued  to  be  sys- 
tematically prosecuted,  the  theory  of  nitro-substitution 
was  evolved,  and  the  knowledge  of  the  applicability  of 
the  new  materials  to  military  requirements  extended. 
But  more  than  forty  years  were  to  elapse  from  the 
time  of  the  first  experiments  before  a  thoroughly  re- 
liable smokeless  powder,  free  from  all  tendency  to 
detonation,  producing  minimum  erosion,  of  good 
keeping  qualities,  and  of  maximum  propulsive  effect, 
was  to  be  obtained. 

To  trace  the  various  steps  of  progress  in  the  deter- 
mination of  the  properties  of  gun-cotton  is  exceed- 
ingly difficult.  It  is  primarily  difficult  for  the  reason 
that  the  base-material  under  investigation  possesses 
an  organic  structure ;  and  because  the  resultant  nitrated 
product  varies  in  chemical  composition  according  to 
strength  and  temperature  of  the  acids  employed  in 
its  preparation,  their  water  content,  duration  of  re- 


ORIGIN1  3 

action,  and  temperature  at  which  the  reaction  is  con- 
ducted. It  is  difficult  secondarily  for  the  reason  that 
the  ultimate  product  of  nitration  is  either  resolvable, 
by  treatment  with  certain  solvents,  into  different  sub- 
components, or  else  is  capable  of  direct  preparation  in 
a  form  soluble  in  one  or  another  solvent;  and  because 
certain  industries,  sciences,  and  professions — the  man- 
ufacture of  explosives,  of  fabrics,  photography,  sur- 
gery— have  required  the  development  of  special  forms 
of  material  and  demanded  special  lines  of  research. 

The  existence  to-day  of  a  very  large  number  of 
unclassified  names  to  denote  the  different  varieties  of 
nitro-cellulose,  serves  as  an  illustration  of  the  necessa- 
rily involved  and  complex  nature  of  such  investigations 
as  have  been  made  for  the  purpose  of  determining  its 
composition,  and  of  the  incompleteness  of  these  inves- 
tigations. The  confusion  in  nomenclature  that  has 
arisen  is  attributable  to  the  fact  that  the  formula  for 
cellulose,  and  therefore  for  the  cellulose  nitrates,  not 
being  established,  investigators  in  different  countries 
started  in  independently  to  determine  simultaneously 
both  the  properties  of  these  compounds  and  their 
chemical  constitutions.  Matters  became  further  in- 
volved through  the  efforts  to  translate  the  accounts  of 
the  work  of  one  investigator  into  the  language  of 
another. 

With  the  view  of  avoiding  confusion  in  the  future  it 
may  be  well  to  anticipate  somewhat  here,  to  indicate 
the  origin  of  the  various  names  applied  to  forms  of 
nitro-cellulose,  to  define  and  classify  them,  and  to 
indicate  such  of  them  as  will  be  employed  hereafter  in 


4  SMOKELESS  POWDER 

the  body  of  the  present  work  ot  denote  those  distinct 
varieties  that  possess  significance  from  the  standpoint 
of  explosive  effect. 

NOMENCLATURE 

Names  may  be  divided  into  classes,  according  to 
origin,  as  follows: 

i. — Those  devised  by  discoverers  to  denote  new 
chemical  compounds.  Thus,  xyloidin,  from  £uAos", 
wood ;  pyroxylin,  from  nvp,  fire,  and  £uAo?,  wood. 

2. — Those  implying  uses  to  which  special  forms  of 
the  material  are  applied,  as  gun-cotton,  collodion-cot- 
ton. 

3. -1— Those  originating  in  references  to  the  theory 
of  nitro--substitution ;  thus,  nitro-cellulose,  mono-,  di-, 
tri-,  tetra-,  penta-,  etc.,  nitro-cellulose. 

4. — Names  based  upon  the  physical  characteristics 
of  the  material,  as  "soluble  nitro-cellulose,"  "insol- 
uble nitro-cellulose,"  "  friable  cottons  "  (Vieille). 

5. — Names  obviously  incorrect  as  to  application  and 
meaning,  as  "  soluble  cotton  "  for  soluble  -nitre-cellu- 
lose; "  insoluble  cotton  "  for  insoluble  nitro-cellulose. 

6. — Generic  names  for  groups  of  varieties  between 
which  differences  in  chemical  composition  were  recog- 
nized as  existing;  thus,  nitro-celluloses  as  opposed  to 
nitro-hydrocelluloses. 

7. — Names  referring  to  chemical  composition  as 
modified  by  extent  and  character  of  nitro-substitution, 
as  "soluble  nitro-cellulose  of  high  nitration,"  of  "low 
nitration." 


ORIGIN  5 

DEFINITIONS 

Cellulose. — The  cell-wall  or  envelope  of  plant-tissues, 
to  which  the  name  cellulose  has  been  applied  as  to  a 
chemical  individual.  Unless  the  contrary  is  stated, 
the  term  cellulose,  as  employed  in  the  present  work, 
refers  to  pure  cotton,  unbleached  and  unspun,  freed  by 
mechanical  treatment  (ginning,  picking,  boiling,  etc.) 
from  wood,  dirt,  greases,  resins,  and  foreign  matter  in 
general;  either  in  the  natural  state,  or  as  waste  product 
from  industrial  processes. 

Nitration. — The  displacement  of  a  number  of  atoms 
of  replaceable  hydrogen  in  cellulose,  and  the  substitu- 
tion therefor  of  the  univalent  radicle  nitryl  (NOa). 
The  term  "  nitration  "  is  also  employed  to  indicate  the 
percentage  of  nitrogen  in  a  given  nitro-cellulose. 

Nitro-cellulose. — Products  resulting  from  the  treat- 
ment of  cellulose  with  strong  nitric  acid  under  the 
condition  that  they  retain  the  cellular  structure  of  the 
original  cotton. 

Nitro-cellulose  of  high  nitration. — Those  forms  of 
nitro-cellulose  in  which  a  relatively  large  number  of 
the  replaceable  hydrogen  atoms  are  replaced  by  nitryl. 

Nitro-cellulose  of  mean  nitration. — Those  forms  of 
nitro-cellulose  in  which  a  mean  number  of  the  replace- 
able hydrogen  atoms  are  replaced  by  nitryl. 

Nitro-cellulose  of  low  nitration. — Those  forms  of 
nitro-cellulose  in  which  a  relatively  small  number  of 
replaceable  hydrogen  atoms  are  replaced  by  nitryl. 

Insoluble  nitro-cellulose. — Those  forms  of  nitro-cel- 
lulose of  high  nitration  insoluble  at  ordinary  atmos- 


O  SMOKELESS  POWDER 

pheric  temperatures  in  a  mixture  of  two  parts  by 
weight  of  ethyl  ether  and  one  part  by  weight  of  ethyl 
alcohol. 

Soluble  nitro-celliilose. — Those  forms  of  nitro-cellu- 
lose  of  low  or  mean  nitration  soluble  at  ordinary  at- 
mospheric temperature  in  a  mixture  of  two  parts  by 
weight  of  ethyl  ether  and  one  part  by  weight  of  ethyl 
alcohol. 

Hydrocellulose. — The  product  obtained  by  exposing 
cotton  to  the  action  of  hydrochloric-acid  fumes ;  or  by 
immersing  it  in  hydrochloric,  dilute  sulphuric,  or  very 
dilute  nitric  acid ;  a  white  pulverulent  mass  which, 
under  the  microscope,  is  seen  to  consist  of  fragments  of 
the  original  fibre  of  modified  cellular  form. 

Nitro-hydrocellulose. — Products  resulting  from  the 
treatment  of  hydrocellulose  with  strong  nitric  acid 
under  the  condition  that  the  resultant  product  retains 
the  cellular  structure  originally  possessed  by  the  hy- 
drocellulose. 

Nitro-hydrocellulose  of  high  nitration. — Those  forms 
of  nitro-hydrocellulose  in  which  a  relatively  large 
number  of  the  replaceable  hydrogen  atoms  are  replaced 
by  nitryl. 

Nitro-hydrocellulose  of  mean  nitration.  —  Those 
forms  of  nitro-hydrocellulose  in  which  a  mean  number 
of  the  replaceable  hydrogen  atoms  are  replaced  by 
nitryl. 

Nitro-hydrocellulose  of  low  nitration. — Those  forms 
of  nitro-hydrocellulose  in  which  a  relatively  small 
number  of  replaceable  hydrogen  atoms  are  replaced  by 
nitryl. 


ORIGIN  7 

Insoluble  nitro-Jiydroccllulose. — Those  forms  of  nitro- 
hydrocellulose  of  high  nitration  insoluble  at  ordinary 
atmospheric  temperatures  in  a  mixture  of  two  parts 
by  weight  of  ethyl  ether  and  one  part  by  weight  of 
ethyl  alcohol. 

Soluble  nitro-hydrocellulose. — Those  forms  of  nitro- 
hydrocellulose  of  low  or  mean  nitration  soluble  at 
ordinary  atmospheric  temperatures  in  a  mixture  of 
two  parts  by  weight  of  ethyl  ether  and  one  part  by 
weight  of  ethyl  alcohol. 

Gun-cotton. — The  military  name  for  those  forms  of 
highly  explosive  nitro-celluloses  employed  in  war,  and 
which  are  generally  mixtures  of  a  large  quantity  of  in- 
soluble with  a  small  quantity  of  soluble  nitro-cellulose 
and  a  very  small  quantity  of  unnitrated  cotton. 

Pyrocellulose. — Soluble  nitro-cellulose  of  high  uni- 
form nitration,  possessing  a  sufficient  content  of  oxy- 
gen to  convert  its  carbon  into  carbonic  oxide  and  its 
hydrogen  into  aqueous  vapor. 

These  terms,  as  defined  above,  will  be  employed  so 
far  as  possible  in  the  body  of  this  treatise.  The  follow- 
ing list  of  synonyms  is  supplied  for  reference : 

TABLE  I 

Name  Synonym 

Nitro-cellulose,  Pyroxyline  or  pyroxylin. 

Insoluble  nitro-cellulose,  Insoluble    gun-cotton  ;  insolu- 

ble cotton. 

Soluble  nitro-cellulose,  Soluble     gun-cotton;     soluble 

cotton;  collodion-cotton;  col- 
lodion-pyroxylin. 

Soluble    nitro-cellulose  of  low         Friable  cotton. 
nitration. 


CHAPTER  II 

EARLIER    VIEWS    AS    TO   NITRO-CELLULOSE    COM- 
POSITION   AND   CONSTITUTION 

EXISTING  knowledge  of  the  composition  and  consti- 
tution of  nitro-cellulose  still  remains  in  a  state  of  great 
confusion.  A  number  of  papers,  scattered  through- 
out the  literature  of  experimental  chemistry,  and 
which  throw  valuable  light  upon  the  subject,  have  been 
published  by  independent  investigators,  while  from 
time  to  time  more  elaborate  articles  summarizing  the 
results  of  early  workers  have  appeared.  At  least  one 
excellent  treatise  upon  cellulose  has  been  published,  * 
but  it  devotes  only  a  few  pages  to  the  consideration 
of  the  nitro-celluloses.  The  reason  for  the  existing 
confusion  is  that  as  yet  no  definite  chemical  structure 
has  been  determined  for  nitro-celluloses;  they  are  re- 
garded as  nitro-substitution  compounds,  as  ethers,  or 
else  their  composition  is  considered  as  still  doubtful. 

If,  however,  the  various  original  experimental  re- 
sults and  the  conclusions  that  have  been  drawn  there- 
from be  examined  in  sequence,  it  will  be  observed  that 
there  does  exist  a  tendency  to  account  for  the  compo- 
sition of  these  bodies  on  a  definite  hypothesis.  There- 

*"  Cellulose,"  Cross  and  Bevan.  London:  Longmans,  Green 
&  Co.,  1895. 

8 


EARLIER    VIEWS  AS    TO   NITRO-CELLULOSE        9 

fore  the  writer,  in  his  endeavor  to  throw  some  light 
upon  ultimate  cellulose-  and  nitro-cellulose  composi- 
tion, will  take  up  for  consideration,  first  of  all,  in 
natural  order  of  succession,  results  obtained  by  a 
number  of  students,  each  of  whom,  in  his  work,  has 
supplied  material  from  which  subsequent  investigators 
have  drawn  important  conclusions. 

Almost  from  the  beginning  of  the  study  of  the  body 
the  existence  of  more  than  one  form  was  recognized. 
Domonte  and  Menard's  discovery  that  pyroxylin  of 
low  nitration  was  soluble  in  ether-alcohol,  while  the 
more  highly  nitrated  variety  remained  insoluble  there- 
in, furnished  a  positive  differentiation  of  nitro-cellu- 
loses  into  two  groups;  Bechamp  showed  that  there 
existed  nitro-celluloses  of  different  nitrations  soluble 
in  ether-alcohol ;  and  the  only  way  of  explaining  the 
existence  of  such  differences,  in  accordance  with 
chemical  theory,  was  by  assuming  that  the  substances 
of  varying  degrees  of  nitration  obtained  consisted  of 
mixtures  of  various  quantities  of  different,  definite, 
chemical  compounds. 

The  numerous  attempts  to  explain  both  the  mode 
of  formation  of  nitro-cellulose  as  well  as  its  constitu- 
tion, and  to  reconcile  results  from  its  analyses,  are  well 
illustrated  by  the  formulae  selected  by  early  investi- 
gators to  represent  its  varieties.  Of  these  formulas, 
numerous  series  exist,  extending  from  the  original 
formula  of  Schonbein,  through  the  later  formulated, 
so-called  mono-,  di-,  and  trinitro-celluloses,  to  the 
series  of  six  nitrates  of  Eder.  At  an  early  date  the 
belief  became  established,  based  in  all  probability  upon 


10  SMOKELESS  POWDER 

analogies  furnished  by  the  nitre-glycerins  and  nitro- 
benzols,  that  nitro-celluloses  were  mixtures  of  nitro- 
substitution  products,  which,  assuming  the  composition 
of  cellulose  as  C6H10OB,  were  formulated  as  the  tri-,  di-, 
and  mononitrates,  with  compositions  C6H,O8(NOa),, 
C8H8O6(NOa)3,  and  C6H9O6(NO,),  respectively.  Of 
these,  trinitro-cellulose  was  considered  as  identical 
with  the  insoluble  variety  of  high  nitration,  and  di- 
nitro-cellulose  with  that  soluble  in  ether-alcohol;  the 
existence  of  the  mononitro-cellulose  was  predicated. 
Certain  reactions  due  to  these  bodies  led  to  a  change 
of  views  concerning  their  chemical  structure.  B6champ 
found  that  nitro-celluloses  dissolved  in  ether-alcohol 
surrendered  nitric  acid  upon  addition  of  potash  or 
ammonia,  with  the  resultant  formation  of  nitro-cellu- 
loses of  lower  nitration ;  he  claimed  for  them  the 
composition  of  ethers.* 

Other  reactions  of  the  nitro-celluloses  tend  to  sup- 
plement this  view  of  their  composition;  e.g.,  ferric 
chloride  and  potassium  and  ammonium  sulphydrates 

*  An  ether  is  one  of  a  class  of  organic  bodies  divided  into  two 
groups  :  (i)  simple  ethers,  consisting  of  two  basic  hydrocarbon 
radicles  united  by  oxygen,  and  corresponding  in  constitution  to 
the  metallic  oxides,  as  CH3OCH3,  methyl  ether,  or  methyl  oxide, 
analogous  to  AgOAg,  silver  oxide  ;  (2)  compound  ethers,  consist- 
ing of  one  or  more  basic  or  alcohol  radicles  and  one  or  more  acid 
or  hydrocarbon  radicles  united  by  oxygen,  and  corresponding  to 
the  salts  of  the  metals,  as  CH3COOC3H5,  ethyl  acetate  or  acetic 
ether,  corresponding  to  CHsCOONa,  sodium  acetate.  Thus,  if  a 
cellulose  be  represented  as  possessing  a  composition  C6Hi0O6, 
and  be  written  as  a  tribasic  alcohol,  C«H7O2  (OH)3,  then,  on  sub- 
stituting nitryl,  Nd,  for  the  replaceable  hydrogen,  we  obtain 
,  a  compound  nitric  ether. 


EARLIER    VIEWS  AS    TO   NITRO-CELLULOSE     II 

(Hadow,  von  Pettenkofer,  cited  by  Guttmann)  occasion 
the  recovery  of  their  cellulose,  while  the  liberated 
nitric  acid  oxidizes  the  iron  of  the  ferric  chloride  and 
transforms  the  sulphydrates  into  nitrates. 

In  1878  Dr.  J.  M.  Eder  conducted  a  series  of  in- 
vestigations into  the  character  and  composition  of  the 
nitro  celluloses  which  has  had  much  influence  upon 
subsequent  formation  of  thought  in  relation  to  the 
character  and  composition  of  these  bodies;  and  from 
the  results  of  his  labors  he  was  led  to  conclude  that 
there  existed  no  less  than  six  distinct  varieties  of  them, 
three  of  which,  the  hexa-,  penta-,  and  di-,  he  was  able 
to  isolate ;  two  of  them,  the  tetra-  and  tri-,  he  obtained 
in  admixture;  the  mononitro-cellulose,  however,  he 
was  unable  to  prepare.  Doubling  the  coefficients  of 
cellulose  to  avoid  fractional  coefficients  in  the  deriva- 
tives, he  formulated  his  series  of  nitrates  as  follows : 
TABLE  II 

Name  Composition 

Cellulose  hexanitrate CiaHi4O4(NO3)« 

Cellulose  pentanitrate C,3H16O5(NO3)6 

Cellulose  tetranitrate CiaHieC^NOa^ 

Cellulose  trinitrate Ci3Hi7O7(NO»)s 

Cellulose  dinitrate CnH16O8(NO3)a 

Cellulose  mononitrate 

Dr.  Eder's  work  constituted  a  purely  scientific  re- 
search into  the  chemical  properties  of  a  group  of 
bodies.  Subsequent  investigations  are  characterized 
by  the  partial  subordination  of  their  scientific  aims  to 
the  demands  of  the  useful  arts.  These  investigations 
are  of  two  kinds,  and  refer  to  the  technical  uses  of  the 
soluble  and  insoluble  varieties  respectively.  Those 


12  SMOKELESS   POWDER 

upon  the  soluble  nitro-celluloses  relate,  for  example,  to 
photography, — to  questions  of  transparency  and  uni- 
formity of  thickness  of  film  ;  those  upon  insoluble  nitro- 
celluloses,  to  the  art  of  war  and  to  the  attainment  of 
the  highest  explosive  effect  consistent  with  the  main- 
tenance of  stability.  The  general  purpose  of  the 
present  work  is  the  study  of  the  physical  and  chemical 
properties  of  nitro-celluloses  and  nitro-cellulose  col- 
loids, their  methods  of  preparation,  and  their  explosive 
qualities;  and  to  the  prosecution  of  this  study  investi- 
gations of  the  second  class  have,  until  recently, 
afforded  the  more  direct  aid.  Conditions  of  research 
have,  however,  been  recently  modified.  For,  whereas 
the  explosives  prepared  from  cotton  were  formerly 
insoluble  nitro-celluloses  (gun-cottons)  susceptible  of 
detonation  as  well  as  of  combustion,  and  employed  in 
mines  and  torpedoes,  yet  in  recent  times  the  field  of 
research  has  been  extended  to  the  soluble  varieties  in 
the  effort  to  secure  a  suitable  base  material  for  the 
preparation  of  anon-detonating,  progressively-burning, 
smokeless  powder. 

The  following  account  of  Eder's  nitrates  (taken 
from  Cross  and  Bevan,  "  Cellulose  "  *)  may  be  quoted 
here : 

"  Hexanitrate,  C12H14O4(NO3)6,  gun-cotton.  In 
the  formation  of  this  body,  nitric  acid  of  1.5  sp.  gr. 
and  sulphuric  acid  of  1.84  sp.  gr.  are  mixed  in  vary- 
ing proportions,  about  3  of  nitric  to  I  of  sulphuric ; 
sometimes  this  proportion  is  reversed,  and  cotton 

*  By  permission  of  Longmans,  Green  &  Co. 


EARLIER   VIEWS  AS    TO  NITRO-CELLULOSE     13 

immersed  in  this  at  a  temperature  not  exceeding 
10°  C.  for  24  hours;  100  parts  of  cellulose  yield 
about  175  of  cellulose  nitrate.  The  hexanitrate  so 
prepared  is  insoluble  in  alcohol,  ether,  or  mixtures 
of  both,  in  glacial  acetic  acid  or  methyl  alcohol. 
Acetone  dissolves  it  very  slowly.  This  is  the  most 
explosive  gun-cotton.  It  ignites  at  i6o°-i7o°  C. 
According  to  Eder  the  mixtures  of  nitre  and  sul- 
phuric acid  do  not  give  this  nitrate.  Ordinary  gun- 
cotton  may  contain  as  much  as  12  per  cent,  of  nitrates 
soluble  in  ether-alcohol.  The  hexanitrate  seems  to 
be  the  only  one  quite  insoluble  in  ether-alcohol." 

"  Pentanitrate,  C12H16O6(NO8)6.  This  composition 
has  been  very  commonly  ascribed  to  gun-cotton. 
It  is  difficult,  if  not  impossible,  to  prepare  it  in  a  state 
of  purity  by  the  direct  action  of  acid  on  cellulose. 
The  best  method  is  the  one  devised  by  Eder,  making 
use  of  the  property  discovered  by  De  Vrij,  that  gun- 
cotton  (hexanitrate)  dissolves  in  nitric  acid  at  about 
80°  or  90°  C.,  and  is  precipitated,  as  the  penta- 
nitrate,  by  concentrated  sulphuric  acid  after  cooling 
to  o°  C. ;  after  mixing  with  a  large  volume  of  water, 
and  washing  the  precipitate  with  water  and  then  with 
alcohol,  it  is  dissolved  in  ether-alcohol  and  again  pre- 
cipitated with  water,  when  it  is  obtained  pure.  This 
nitrate  is  insoluble  in  alcohol,  but  dissolves  readily 
in  ether-alcohol,  and  slightly  in  acetic  acid.  Strong 
potassa  solution  converts  this  nitrate  into  the  di- 
nitrate,  C1.H,.Oi(NO.)1." 

"The  tetra-  and  trinitrates  (collodion-pyroxylin) 
are  generally  formed  together  when  cellulose  is 


14  SMOKELESS   POWDER 

treated  with  a  more  dilute  nitric  acid,  and  at  a  higher 
temperature,  and  for  a  much  shorter  time  (13-20 
minutes),  than  in  the  formation  of  the  hexanitrate. 
It  is  not  possible  to  separate  them,  as  they  are  sol- 
uble to  the  same  extent  in  ether-alcohol,  acetic  ether, 
acetic  acid,  or  wood-spirit.  On  treatment  with  con- 
centrated nitric  and  sulphuric  acids,  both  the  tri-  and 
tetranitrates  are  converted  into  pentanitrate  and  hexa- 
nitrate. Potassa  and  ammonia  convert  them  into 
dinitrate." 

"Cellulose  dinitrate,  CiaH18O8(NO,)a,  is  formed 
by  the  action  of  alkalies  on  the  other  nitrates,  and 
also  by  the  action  of  hot  dilute  nitric  acid  on  cellu- 
lose. The  dinitrate  is  very  soluble  in  alcohol-ether, 
acetic  ether,  and  in  absolute  alcohol.  Further  action 
of  alkalies  on  the  dinitrate  results  in  a  complete 
decomposition  of  the  molecule,  some  organic  acids 
and  tarry  matters  being  formed." 

The  next  after  Eder  to  increase  our  knowledge  of 
the  character  and  relationships  of  the  members  of  the 
nitro-cellulose  series  was  M.  Vieille  (Comptes  Rendus, 
95,  132),  the  eminent  French  savant,  whose  efforts  (in 
collaboration  with  M.  Sarrau)  were  crowned  with 
success  in  the  production  and  establishment  of 
the  manufacture  of  a  successful  smokeless  powder  in 
France.  M.  Vieille's  researches  were  published  in 
part  in  the  French  official  journal  of  explosives,  the 
Memorial  des  Poudres  et  Salpetres,*  a  translation  of 

*  "  Recherches  sur  la  Nitrification  du  Coton,"  by  M.  Vieille, 
Ingenieur  des  Poudres  et  Salpetres,  Vol.  II.,  1889;  Paris  : 
Gauthiers-Villars  et  Fils. 


EARLIER  VIEWS  AS    TO  NITRO-CELLULOSE     15 

the  article  referred  to  constituting  Appendix  I  of  the 
present  work. 

Vieille's  method  consisted  in  selecting  acid  mix- 
tures of  specified  standard  strengths,  nitrating  under 
regularly  controlled  conditions  as  to  mass,  time,  and 
temperature,  determining  the  nitration  of-  the  resul- 
tant products,  and  plotting  upon  diagrams  the  resul- 
tant nitrations  as  referred  to  the  strengths  of  the  acid 
mixtures  used  to  produce  them.  In  this  manner 
he  was  enabled  to  recognize  a  tendency  of  nitration 
towards  groupings  or  discontinuities,  rather  than 
towards  progressively  increasing  nitration,  advancing 
in  measure  with  increase  in  strength  of  acids ;  and  he 
interpreted  this  tendency  as  indicating  the  existence 
of  a  number  of  definite  cellulose  nitrates.  He  sum- 
marizes the  results  of  his  work  as  follows : 

"In  order  to  account  completely  for  the  different 
changes  (groupings,  discontinuities)  by  the  production 
of  nitro-products  corresponding  to  definite  formulae,  the 
equivalent  of  nitro-cellulose  must  be  quadrupled.  Nitro- 
celluloses  corresponding  to  such  formulae  agree  with 
the  theoretical  yields  of  nitrogen  dioxide  per  gram  of 
material  indicated  in  the  following  table,  and  which 
correspond  either  to  the  discontinuities  to  which  we 
have  alluded,  or  else  to  a  change  of  physical  properties. " 

While  Dr.  Eder  formulated  six  varieties  of  nitrated 
material,  doubling  the  coefficients  of  cellulose  by 
writing  it  CiaH20O10,  instead  of  C,H10O6,  M.  Vieille 
formulates  no  less  than  eight  compounds,  to  express 
which  he  quadruples  coefficients,  writing  cellulose  as 
Ca4H40Oa..  He  thus  obtains: 


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SMOKELESS  PO  WDER 


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EARLIER   VIEWS  AS    TO   NITRO-CELLULOSE     I/ 

To  illustrate  the  accordance  of  theory  with  prac- 
tice, the  content  of  nitrogen  (dioxide),  as  it  should 
exist  according  to  theory,  is  compared  in  each  case 
with  that  actually  determined  from  practical  experi- 
ment. From  the  above  there  would  appear  to  be 
two  varieties  of  gun-cotton  insoluble  in  ether-alcohol, 
two  varieties  of  soluble  nitro-celluloses,  and  a  number 
of  varieties  of  nitro-celluloses  of  lower  nitration.  M. 
Vieille's  paper  was  published  shortly  after  the  official 
announcement  by  the  French  Government  of  the  de- 
velopment and  successful  establishment  of  the  manu^ 
facture  of  an  efficient  smokeless  powder,  these  results, 
being  the  declared  fruits  of  M.  Vieille's  researches, 
and  it  is  therefore  authoritative. 

The  points  to  which  attention  are  especially  called 
in  M.  Vieille's  work  are  the  quadrupling  of  the  expo- 
nents of  cellulose,  and  the  formulation  of  as  many  as 
eight  varieties  of  its  nitro-derivatives. 

The  abandonment  of  the  old  types  of  smoke-form- 
ing powders  that  had  been  in  use  for  hundreds  of 
years,  and  the  substitution  therefor,  by  the  French 
government,  of  a  new  and  efficient  smokeless  powder, 
was  a  step  that  naturally  attracted  the  attention  of  all 
civilized  powers.  The  composition  of  the  French 
powders  and  their  methods  of  manufacture  remained 
carefully  guarded  secrets.  Efforts  to  achieve  similar 
results  were  at  once  inaugurated  in  other  countries, 
and  the  period  of  inactivity  following  the  abandon- 
ment of  efforts  to  employ  gun-cotton  as  a  propellant 
gave  way  to  one  of  marked  activity  in  all  that  related 
to  the  study  of  explosives.  Shortly  after  the  an- 


1 8  SMOKELESS  POWDER 

nouncement  of  the  results  obtained  in  France,  the 
Russian  government  commissioned  Professor  D.  Men- 
dele*ef,  a  chemist  who  had  already  achieved  world- 
wide reputation  as  the  expounder  of  the  Periodic 
Law  of  existence  of  the  elements,  to  conduct  a  series 
of  researches  with  a  view  to  the  production  of  an 
efficient  smokeless  powder  for  Russia.  As  the  result 
of  his  labors  Professor  Mendeleef  succeeded  in  de- 
veloping a  powder  called  by  him  "  pyrocollodion," 
which  proved  satisfactory,  and  which  was  adopted 
in  Russia  for  use  in  arms  of  all  calibres.  As  in  the 
case  of  its  predecessor  in  France,  the  composition  and 
method  of  manufacture  of  pyrocollodion  remain  care- 
fully-guarded national  secrets.  Outlines  of  ballistic 
results  have  been  published,  however,  and  it  is  by 
these  that  the  next  light  is  thrown  upon  the  composi- 
tion of  nitro-celluloses. 

The  scope  of  Professor  Mendeleef's  work,  and  the 
character  of  the  analytical  methods  followed  by  him, 
may  be  ascertained  from  an  examination  of  a  paper 
published  by  him,  my  translation  of  which  constitutes 
Appendix  II  of  the  present  work.  In  relation  to 
the  structure  of  the  nitro-celluloses  he  states : 

"  In  all  aldehydes,  beginning  with  the  formic  and 
the  acetic,  a  tendency  towards  polymerization  is  to  be 
noted,  due,  doubtless,  to  the  property  of  aldehydes 
of  entering  into  various  combinations  (with  H2O, 
NaHSO3,  etc.);  whence  the  composition  C6H,0OB, 
containing  an  aldehyde  grouping,  should  also  possess 
this  property,  so  far  as  relates  thereto.  We  may 
therefore  safely  assume  that  the  molecular  composi- 


EARLIER   VIEWS  AS    TO   NITRO-CELLULOSE      1 9 

tion  of  cellulose,  judging  from  its  properties,  is  poly- 
merized, i.e.,  it  is  of  the  form  C6MH10MO6M,  where  n  is 
probably  very  great." 

It  will  be  seen  from  the  foregoing  that  in  their  ef- 
forts to  explain  the  atomic  constitution  of  nitro-cellu- 
lose,  investigators  have  invariably  been  led  to  increase 
the  common  multiple  of  the  elements  entering  into 
the  composition  of  cellulose,  until  finally  Mendele"ef 
states  as  his  opinion  that  this  multiple  may  be  very 
great  through  reason  of  the  presence  of  certain  ten- 
dencies towards  polymerization.  It  is  interesting  to 
observe  how  different  chemists  have  been  led  to  es- 
tablish conclusions  as  to  the  existence  of  compounds 
corresponding  to  the  formulae  they  have  written. 
Eder  dissolves  out  of  gun-cotton  its  soluble  content, 
and  as  the  result  of  the  analysis  of  the  remaining  por- 
tion writes  its  formula  as  double  tri-,  or  hexanitro- 
cellulose,  C12H14(NO2)6O10;  he  isolates  from  cotton 
treated  with  weaker  acids,  a  compound  corresponding 
in  content  of  nitrogen  to  what  a  body  of  constitution 
ClaH16(NO3)6O10,  a  pentanitro-cellulose,  should  give, 
and  obtains  through  the  agency  of  solution  a  nitro- 
cellulose precipitate  satisfying  the  desired  conditions. 
He  also  obtains,  by  employing  acids  of  still  further 
reduced  strengths,  a  body  of  variable  composition 
which  he  regards  as  a  mixture  of  tetra-  and  trinitro- 
celluloses,  but  does  not  succeed  in  isolating  the  two 
distinct  bodies  from  the  mixture.  Vieille  employs 
mixtures  of  acids  increasing  in  strength  progressively ; 
continues  the  process  of  nitration  through  a  period  of 
time  sufficiently  long  to  insure  the  total  conversion  of 


20  SMOKELESS  POWDER 

the  cellulose  into  nitro-cellulose  (as  shown  by  the  em- 
ployment of  a  solution  of  iodine  in  potassium  iodide 
as  an  indicator  of  free  cellulose);  refers  to  coordinate 
axes  the  results  of  each  observation,  employing 
strengths  of  acids  as  abscissae,  and  numbers  of  cubic 
centimetres  of  nitric  oxide  evolved  as  ordinates. 
Upon  comparing  results  he  notes  a  tendency  towards 
the  existence  of  progressive  steps  in  nitration;  i.e., 
for  an  acid  varying  somewhat  above  and  below  a  cer- 
tain point  in  strength  there  appears  to  be  formed  a 
definite  product  of  nitration.  Taking  into  account  the 
number  of  such  steps  observed  and  their  distances 
apart,  he  formulates  the  series  of  compounds  enumer- 
ated in  a  preceding  paragraph. 


CHAPTER    III 

THE    CONCEPTION    OF     PROGRESSION     IN    RELA- 
TION  TO   COMPOSITION   AND  CONSTITUTION 

CELLULOSE  is  distinguishable  from  other  materials 
employed  for  purposes  of  nitration  by  the  possession 
of  a  continuous,  complex,  and  definite  cell  struc- 
ture. The  plant  producing  it  has  developed  by 
growth  from  the  protoplasmic  state,  through  influences 
of  soil,  atmosphere,  and  sunlight;  after  its  death  the 
cellulose  tissues  remain,  the  skeleton  of  the  once  liv- 
ing organism,  possessing  a  structure  bestowed  by  suc- 
cessive growth  processes  and  not  by  any  definite  and 
general  chemical  change  occurring  at  any  stated  time. 
It  is  this  remaining  tissue,  an  organization  of  cells 
infinite  in  their  variety  and  form,  that  constitutes  the 
base  material  employed  for  nitration.  We  may  pro- 
ceed to  nitrate  it  in  various  ways ;  we  may  first  par- 
tially destroy  or  disintegrate  the  cell  structure  (con- 
vert it  into  hydrocellulose) ;  the  nitration  may  be  con- 
ducted at  various  temperatures  and  continued  for 
different  lengths  of  time  with  the  employment  of  vari- 
ous acid  mixtures  of  different  strengths,  and  with  the 
use  of  different  relative  quantities  of  cotton  and  acids. 
If  all  of  these  governing  conditions  be  taken  account 
of,  and  if  proper  allowance  be  made  for  their  effect, 

zi 


22  SMOKELESS  POWDER 

we  may  predicate  for  the  nitrated  product  an  exact 
composition  and  exact  qualities;  if  any  of  them  be 
overlooked,  we  lose  control  of  physical  character  and 
chemical  composition  of  the  final  product. 

The  method  of  accounting  for  the  composition  of 
nitro-cellulose  by  assuming  it  to  consist  of  a  mixture 
of  the  different  members  of  a  graded  series  of  cellulose 
nitrates — themselves  definite  chemical  compounds — 
was  a  rational  procedure  in  accordance  with  established 
chemical  usage;  yet  there  existed  grave  difficulties  in 
the  way  of  maintaining  such  views.  In  the  first 
place,  the  members  of  the  series  could  not  be  sepa- 
rated from  one  another.  Eder  was  unable  to  separate 
cellulose  tetra-  and  trinitrates.  The  impossibility  of 
resolving  a  given  nitro-cellulose  into  definite  quantities 
of  the  various  compounds  formulated  by  Vieille,  Eder, 
or  their  predecessors,  is  generally  recognized  by  every 
investigator  to-day.  In  the  second  place,  the  concep- 
tion of  a  definite  period  of  time  being  required  to  ef- 
fect nitration  is  inseparably  connected  with  the  forma- 
tion of  these  bodies.  Thus  properly  nitrated  gun- 
cotton  consists  of  a  large  quantity  of  insoluble  with  a 
small  quantity  of  soluble  and  a  very  small  quantity  of 
unnitrated  cotton ;  but  if  nitration  be  arrested  before 
completion,  there  results  a  mixture  of  different 
quantities  of  nitrated  and  unnitrated  cotton. 

That  the  nitration  of  cellulose  is  a  gradual  progres- 
sive process,  advancing  from  incipiency  through  lapse 
of  time  towards  completion,  was  the  next  theory  ad- 
vanced. This  change  in  treatment  of  the  problem, 
which  virtually  led  to  the  abandonment  of  the  old 


PROGRESSION  23 

simple  formulation  advocated,  is  discussed  with  great 
clearness  by  M.  Bruley,  a  French  Government  chem- 
ist, in  a  paper  entitled  "  Sur  la  Fabrication  des  Cotons 
Nitres,"  published  in  the  Memorial  des  Poudres  et 
Salpetres  (Vol.  VIII,  1895-6),  my  translation  of  which 
constitutes  Apendix  III  of  the  present  work. 

For  purposes  of  elucidation,  Bruley's  work  will  be 
considered  comparatively,  in  relation  to  what  has  been 
accomplished  by  others.  The  first  investigators 
treated  cellulose  with  nitric  acid  direct,  and  obtained 
a  product  to  which  they  endeavored  to  ascribe  a  for- 
mula; their  successors  demonstrated  the  existence  of 
more  than  one  variety  of  nitro-cellulose,  and  formulated 
a  series  of  compounds.  The  various  acid  mixtures 
employed  in  these  researches  may  be  divided  into  two 
classes:  those  composed  of  nitric  acid  and  water  taken 
in  various  proportions,  and  those  containing  sulphuric 
acid  in  additiori  to  nitric  acid  and  water.  It  was  un- 
derstood how  the  absorptive  action  of  the  sulphuric 
acid  rendered  possible  the  formation  of  cellulose  ni- 
trates of  higher  nitration  than  those  that  could  be  ob- 
tained by  the  employment  of  concentrated  nitric  acid 
alone.  But  mixtures  of  concentrated  nitric  and  sul- 
phuric acids  necessarily  contain  water,  anhydrous  sul- 
phuric acid  being  a  solid  and  anhydrous  nitric  acid 
being  impossible  to  prepare ;  while  with  the  more 
highly  diluted  mixture  of  the  two  acids  cellulose 
nitrates  identical  with  those  formed  with  nitric  acid 
and  water  alone  could  be  formed  ;  therefore  the  widest 
range  of  nitration  resulted  from  the  employment  of 


24  SMOKELESS  POWDER 

mixtures    containing    nitric   and    sulphuric  acids   and 
water. 

Vieille  had  already  studied  the  nitro-products 
formed  by  the  use  of  mixtures  containing  various  pro- 
portionate quantities  of  nitric  and  sulphuric  acids  of 
definite  strengths.  Bruley's  investigations  covered  the 
broader  field  resulting  from  the  employment  of  mix- 
tures of  the  three  elements,  in  which  the  quantity  pres- 
ent of  each  element  varied  in  all  practicable  proportions 
in  reference  to  the  quantities  of  the  other  two.  The 
scope  of  the  latter  work  may  be  graphically  indicated 
as  follows : 


15. 


PROGRESSION  2$ 

Let  OX  and  OY  be  coordinate  axes.  On  OY  lay 
off  OY't  which  divide  into  one  hundred  equal  parts; 
and  let  OY"  represent  the  number  of  parts  of  nitric 
acid  to  one  hundred  parts  of  sulphuric  acid.  Then 
Y"X"',  parallel  to  OX,  will  be  the  locus  of  all  points 
corresponding  to  mixtures  in  which  the  amounts  of 
nitric  and  sulphuric  acids  present  bear  the  definite 

OY" 
ratio        7   to  each  other.      On   OX  lay  off  OX'  and 


divide  it  into  one  hundred  equal  parts,  and  let  OX" 
represent  the  number  of  parts  of  water  to  one  hundred 
parts  of  sulphuric  acid.  Then  X"  Y'"  ,  parallel  to  OY, 
will  be  the  locus  of  all  points  corresponding  to  mix- 
tures in  which  the  quantities  of  water  and  sulphuric  acid 

OX" 
present  bear  the  definite  ratio    ~,  to  one  another. 


The  point  P,  in  which  the  lines  Y"X'"  and  X"  Y'"' 
intersect,  corresponds  to  a  mixture  containing  definite 
quantities  of  nitric  acid,  sulphuric  acid,  and  water. 
The  area  OY'OX'  is  a  rectangle,  every  point  of  which 
corresponds  to  some  one  combination  of  the  three 
elements.  M.  Bruley  explores  this  area  by  choosing 
a  number  of  approximately  equidistant  points  dis- 
tributed over  its  surface,  preparing  the  acid  mixtures 
corresponding  to  them,  and  determining  the  nitration 
and  solubility  of  the  nitro-celluloses  prepared  from 
these  mixtures.  Proceeding  in  this  manner,  and  join- 
ing points  of  equal  nitration,  he  maps  out  a  series  of 
parallel  or  nearly  parallel  curves,  between  which  are 
included  areas  of  equal  or  similar  solubility.  The  fol- 


26 


SMOKELESS  POWDER 


lowing  diagram,  taken  from  M.  Bruley's  work,  illus- 
trates the  method : 
Y 


60- 


55- 


350-1 


5 

CO 

fe« 

f- 

§ 

030 


325 


015 

cc 

2 


XI 


5  1015202530354045 

PROPORTION  OF  WATER  TO  100  PARTS  OF  SULPHURIC  ACID 

The  Roman  numeral  is  the  serial  number  of  experiment;  the 
upper  Arabic  numeral,  the  nitration  in  cubic  centimetres  of  NOa, 
the  second,  the  solubility;  and  the  third,  when  given,  the  vis- 
cosity. 

The  nearer  the  points  corresponding  to  nitrations 
lie  to  the  line  Ef>  which  is  the  locus  of  mixtures  con- 


PROGRESSION'  2/ 

taining  the  least  possible  quantities  of  water,  the 
higher  the  nitrations.  The  area  is  divided  into  belts 
corresponding  to  mixtures  forming  insoluble  nitro- 
celluloses,  "  intermediate  "  nitro-celluloses,  collodions 
of  higher  and  of  lower  nitration,  and  ' '  friable  "  cottons. 
The  published  investigations  do  not  consider  mixtures 
containing  more  than  55  parts  of  nitric  to  100  parts  of 
sulphuric  acid,  M.  Bruley  stating  that  mixtures  con- 
taining more  than  this  relative  proportion  of  nitric 
acid  are  "  not  practicable  commercially  from  their  in- 
creased cost  "  ;  nor  those  containing  less  than  15  parts 
of  nitric  to  100  parts  of  the  sulphuric  acid  present; 
in  these  nitration  proceeds  with  exceeding  slowness. 
Similarly,  mixtures  containing  less  than  35  per  cent, 
of  water,  compared  with  the  quantity  of  sulphuric  acid 
present,  embrace  all  those  capable  of  producing  nitra- 
tions higher  than  those  of  "friable"  cottons;  while 
the  lower  limit  of  water  is  fixed  by  the  strength  of 
the  strongest  acids  commercially  obtainable. 

Besides  nitration  and  solubility,  a  new  characteristic 
of  the  nitrated  product  is  here  introduced, — viscosity, 
— as  determined  by  the  rate  of  flow,  in  drops  per  min- 
ute, through  a  standard  orifice,  of  a  standard  solution 
of  the  collodion  under  examination.  M.  Bruley 
states  that  increased  temperature  of  nitration,  as  well 
as  continued  pulping  and  washing  in  warm  water, 
all  have  the  effect  of  diminishing  the  viscosity  of  the 
collodions  formed  from  nitro-cellulose ;  but  he  does 
not  discuss  the  practical  bearing  of  this  fact  on  the 
manufacture  of  colloids. 

M.  Bruley  also  discusses  briefly  relations  of  time 


28  SMOKELESS  POWDER 

and  temperature  to  nitration.  The  duration  of  the 
reaction  is  found  to  be  the  more  prolonged  the  smaller 
the  quantity  of  nitric  acid  present  in  the  nitrating  mix- 
ture; an  immersion  of  two  hours  is  found  to  suffice, 
in  general,  for  the  production  of  the  soluble  nitro- 
celluloses ;  but  as  much  as  eight  to  ten  hours  are  re- 
quired to  complete  the  nitration  of  gun-cotton.  A 
comparison  is  made  of  nitrations  conducted  at  three 
different  temperatures,  employing  the  same  acids  and 
cotton ;  and  the  conclusion  is  reached  that,  in  the 
case  of  soluble  nitro-celluloses,  increase  of  tempera- 
ture during  dipping  and  reaction  increases  ultimate 
nitration  and  solubility;  while  for  gun-cotton,  though 
the  effect  of  temperature  upon  solubility  is  less  dis- 
tinctly marked,  yet  high  temperatures  have  the  effect 
of  increasing  solubilities. 

During  the  years  1895  and  1896,  I  conducted  series 
of  experiments  at  the  Naval  Torpedo  Station,  at  New- 
port, Rhode  Island,  with  the  view  to  the  production 
of  a  nitro-cellulose  base  suitable  for  conversion,  by 
direct  colloidization,  into  an  efficient  smokeless  pow- 
der.* The  problem  presented  itself  in  the  form  of  an 
attempt  to  transform  well-known  types  of  nitro-cellu- 
loses, with  or  without  the  addition  of  solid,  non- 
colloidable  ingredients,  and  by  the  use  of  standard  sol- 
vents, into  colloid  powders;  and  it  ultimately  resolved 
into  an  effort  to  overcome  certain  ballistic  inconven- 
iences, the  existence  of  which  was  not  recognized  when 
the  experiments  were  begun.  In  the  endeavor  to  over- 

*I  have  continued  experimenting  in  this  field,  at  intervals, 
ever  since  this  time. — J.  B.  B. 


PROGRESSION  2$ 

come  these  inconveniences,  it  became  apparent  that 
there  was  little  hope  of  preparing  from  the  old  mate- 
rials a  powder  capable  of  fulfilling  service  require- 
ments; and  the  results,  wholly  negative,  of  elaborate 
and  exhaustive  series  of  experiments  with  the  old 
materials,  forced  me  to  the  conclusion  that,  if  a  suit- 
able powder  were  developed,  it  could  only  be  through 
the  discovery  of  a  new  form  of  nitro-cellulose  capable 
of  colloidization,  and  which  would  possess  physical 
and  chemical  properties  not  pertaining  to  any  hitherto 
existing  known  form  of  this  substance. 

As  the  result  of  my  labors  I  succeeded  in  develop- 
ing such  a  new  form  of  nitro-cellulose,  which  I  was 
able  to  convert  directly,  by  colloidization,  without 
addition  of  other  ingredient,  into  a  colloid  smokeless 
powder,  suitable  for  arms  of  all  calibres.  With  this 
powder  I  conducted  extended  series  of  experiments, 
testing  and  establishing  its  keeping  qualities,  and  stand- 
ardizing weights  of  charge  and  dimensions  of  grain  for 
the  different  calibres  of  guns.  Its  manufacture  was 
established  on  a  commercial  scale  at  the  Torpedo  Sta- 
tion, at  Newport,  Rhode  Island,  where  the  represen- 
tatives of  the  various  private  powder-manufacturing 
establishments  were  instructed  in  the  method  of  prep- 
aration of  the  new  material.*  Subsequently  these  firms 
established  plants  of  their  own  on  a  scale  far  larger 

*  At  this  time  (1894-1897)  the  Naval  Torpedo  Station,  at  New- 
port, Rhode  Island,  was  under  the  command  of  Captain  George 
A.  Converse,  U.  S.  Navy,  to  whose  ability  as  an  administrator, 
as  well  as  mechanical  skill  as  a  specialist,  the  successful  devel- 
opment of  smokeless  powder  is  largely  attributable. 


3O  SMOKELESS  POWDER 

than  that  undertaken  at  Newport ;  and  finally  an  ap- 
propriation was  secured  for  the  Navy,  sufficient  for  the 
erection  of  a  plant  large  enough  to  enable  this  branch 
of  the  service  to  manufacture  an  appreciable  share  of 
the  powder  consumed  afloat. 

The  steps  leading  up  to  the  development  of  the 
new  nitro-cellulose  are  cited  here  in  relation  to  the 
light  they  throw  upon  ultimate  cellulose  and  nitro- 
cellulose structure.  Taken  in  order  of  approximate 
sequence  they  may  be  outlined  as  follows: 

i. — Powders  were  prepared  by  colloiding  insoluble, 
soluble,  and  mixtures  of  insoluble  and  soluble  nitro- 
celluloses  in  acetone  (both  varieties  of  nitro-cellulose 
readily  colloid  in  this  solvent),  forming  the  resultant 
material  into  strips  of  different  thicknesses,  firing 
charges  of  different  weights  of  each  thickness  from 
standard  guns,  and  tabulating  resultant  velocities  and 
pressures.  Besides  the  pure  colloids  thus  obtained 
there  were  experimented  with  other  colloids  having  in- 
corporated into  them  various  percentages  of  barium  and 
potassium  nitrates,  both  deposited  from  solution  and 
employed  in  the  dry  pulverulent  state.  It  was  observed 
that  the  addition  of  the  nitrates  led  to  the  develop- 
ment of  smoke,  but  increased  the  value  of  V/P,  the 
ratio  of  the  maximum  pressure  to  the  initial  velocity 
realized. 

2. — A  large  quantity  of  gun-cotton,  then  stored  at 
the  Torpedo  Station,  was  available  for  conversion  into 
powder.  It  was  found  that  different  manufactured 
lots  of  this  material  produced  powders  differing  widely 
in  ballistic  properties.  To  determine  the  cause  of 


PROGRESSION  3 1 

these  differences,  I  took  blocks  of  each  gun-cotton  in 
store  (some  fifty  odd  lots),  washed,  dried,  and  sifted 
each  sample, — the  washing  to  remove  the  sodium  car- 
bonate,— colloided  each  with  the  same  acetone,  formed 
the  resultant  masses  into  small  rectangular  grains  of 
the  same  dimensions  and  dried  them.  I  then  placed 
one- gram  weights  of  each  small  lot  upon  slips  of  glass 
and  ignited  them  in  the  open.  The  ashes  remaining 
after  combustion  differed  very  greatly  among  them- 
selves, some  assuming  the  form  of  a  fine  white  resi- 
due, others  of  a  sooty  mass  of  unconsumed  carbon. 
Upon  comparing  the  ash  residues  with  the  results  of 
the  complete  chemical  analyses  of  the  original  cottons 
subsequently  made,  I  found  that,  for  the  cases  where 
carbon  was  deposited,  the  gun-cottons  from  which  the 
powder  had  been  made  contained  an  abnormally  large 
quantity  of  free  unnitrated  cotton,  the  existence  of 
which  had  not  hitherto  been  suspected. 

3. — Those  lots  of  gun-cotton  containing  large  quanti- 
ties of  free  unnitrated  cotton  being  eliminated,  experi- 
ments with  powders  prepared  from  the  remaining  lots 
were  continued.  Ballistic  differences  were  still  found  to 
obtain,  although  less  marked  than  those  primarily  ob- 
served. Upon  comparing  the  nitration  of  the  original 
gun-cottons, — which  differed  among  themselves  con- 
siderably, ranging  between  N  =  13.4  and  N  =  12.4, — 
with  the  ballistic  results  from  the  powders  prepared  from 
them,  it  was  found  that  the  brusquer  powders,  which 
developed  high  pressures  as  corresponding  to  compar- 
atively low  velocities,  were  prepared  from  gun-cottons 
of  highest  nitration.  It  occurred  to  me,  therefore, 


32  SMOKELESS  POWDER 

that  uniformity  in  ballistic  conditions  might  be  pre- 
served through  the  maintenance  of  mean  nitration, 
i.e.,  by  blending  different  lots  of  nitro-celluloses  to- 
gether, so  that  the  mean  nitrogen  contents  of  all 
blends  should  be  maintained  a  constant ;  at  the  same 
time  providing  that  dimensions  of  powder-grains  and 
weights  of  charge  remained  equal.  The  truth  of  this 
theoretical  assumption  was  abundantly  sustained  by 
the  results  of  practical  experiment,  and  the  problem 
of  the  attainment  of  ballistic  uniformity,  using  gun- 
cotton  and  the  old  forms  of  soluble  nitro-celluloses  as 
basis  materials  for  the  manufacture  of  colloid  powder, 
was  solved.  Bearing  in  mind  the  actual  nitrations  of 
the  various  lots  of  gun-cottons  on  hand,  I  chose  a 
mean  of  12.75  Per  cent.  N  as  a  standard  of  nitration, 
and  blended  the  successive  lots  to  this  figure,  adding 
soluble  nitro-cellulose  when  it  became  necessary  to  re- 
duce lots  of  especially  high  nitration  down  to  the  stan- 
dard. 

4. — I  observed,  as  the  result  of  experiment,  that  the 
velocity  corresponding  to  a  given  bore-pressure  could 
be  increased  by  incorporating  oxygen-carriers,  such  as 
barium  and  potassium  nitrates,  in  certain  percentages 
into  colloid  powders;  and  to  such  an  extent  that  for 
a  pressure  of  fifteen  tons  a  gain  of  about  300  foot- 
seconds  could  be  realized.  I  attributed  this  difference 
in  ballistic  effect  to  an  accelerative  action  due  to  the 
oxidation  of  the  products  of  combustion  of  the  nitro- 
cellulose after  their  evolution  in  the  bore  of  the  gun 
and  before  leaving  the  gun,  by  the  gaseous  oxides  of 


PROGRESSION  33 

nitrogen  evolved  from  the  metallic  nitrates.*  As  the 
bodies  to  which  accelerative  effect  was  attributable 
were  free,  inert  particles  distributed  throughout  the 
substance  of  the  colloid,  I  argued  that  free,  uncol- 
loided  gun-cotton  distributed  throughout  an  ether- 
alcohol  colloid  of  soluble  nitro-cellulose  would  produce 
the  same  effect.  Experiments  with  free  gun-cotton  as 
an  "  accelerator"  proved  failures,  however,  practically 
no  ballistic  difference  being  observed  between  the  ac- 
tion of  the  ether-alcohol  colloid  of  the  soluble,  contain- 
ing free  insoluble  nitro-cellulose  and  certain  other  col- 
loids of  the  same  in  which  both  ingredients  were  present 
in  the  colloid  state.  The  fact  was  that  both  the  sol- 
uble and  insoluble  forms  of  nitro-cellulose  were,  in 
both  cases,  consumed  away  at  practically  the  same  rate. 
5. — The  effort  to  prepare  powders  from  colloided 
soluble  nitro-celluloses  into  which  uncolloided  insoluble 
nitro-cellulose  was  incorporated  as  an  accelerator,  led 
to  extended  series  of  experiments  with  ether-alcohol 
colloids.  These  proved  at  first  difficult  to  manufacture, 
but,  once  prepared,  were  found  manifestly  superior  to 
the  acetone  colloids,  as  they  were  extremely  tough 
and  well  capable  of  resisting  disintegration  in  the  gun 
at  the  instant  of  firing, — in  which  regard  the  brittle 
acetone  colloids  had  not  proved  altogether  satisfac- 
tory. Actual  experiments  in  firing  had  also  shown 
that  the  greater  the  quantity  of  uncolloided  (insoluble) 

*  See  Appendix  IV,  which  is  a  reprint  of  my  paper  entitled 
"Development  of  Smokeless  Powder,"  published  in  the  Proceed- 
ings of  the  U.  S,  Naval  Inst.,  in  which  the  subject  of  acceleration 
is  treated  at  some  length. 


34  SMOX2LESS  POWDER 

nitrocellulose  present  in  an  ether-alcohol  colloid 
powder,  the  brusquer  the  powder  proved,  developing 
a  higher  bore-pressure  as  corresponding  to  the  muzzle 
velocity  realized.  But,  in  order  to  maintain  a  standard 
nitration, — explosive  strength, — it  was  necessary  to 
have  present  always  a  considerable  quantity  of  the  un- 
colloided  (insoluble)  form  of  nitro-cellulose.  As  this 
was  objectionable  for  the  above  reason,  I  therefore 
began  experimenting,  to  see  how  far  the  nitration  of 
the  soluble  nitro-cellulose  could  be  raised, — with  the 
view  of  minimizing  the  amount  of  insoluble  nitro- 
cellulose that  would  be  required 

6. — I  also  made  investigations  in  another  line,  and 
conducted  firing  trials  with  a  series  of  powders  pre- 
pared from  nitro-hydrocelluloses.  A  note  upon  the 
constitution  of  this  body  may  be  pertinent  here. 

When  cotton  is  exposed  to  the  action  of  hydro- 
chloric acid,  in  the  form  of  gas  or  of  concentrated 
aqueous  solution,  it  undergoes  a  change  of  form  and 
composition,  being  converted  into  a  material  known  as 
hydrocellulose,  the  composition  of  which  has  been 
variously  regarded.  Viewed  as  a  substitution  product, 
it  is  formulated  as  a  cellulose  hydrate  (Girard,  cited  by 
Cross  and  Bevan) ;  considered  physically,  it  appears  to 
consist  of  an  aggregation  of  fragments  of  the  cells 
from  which  the  original  cellulose  was  built  up.  The 
fibres  seem  attacked  along  planes  where  their  sub-, 
stance  is  most  readily  susceptible  of  decomposition  by 
the  acid  and  are  separated  from  one  another;  the  ac- 
tion of  the  acid  appears  to  be  a  cutting  of  cell-joints 
over  planes  of  weakness,  whereby  the  fibres  are  di- 


PROGRESSION  35 

vided  into  small  lengths  which  are  clearly  visible  un- 
der the  microscope.  (There  would  thus  seem  to  be 
some  portions  of  the  cell  more  readily  susceptible  to 
attack  than  other  portions.)  If  the  process  be  incom- 
plete, partial  separation  only  occurs,  long  unattacked 
fibres  remaining  in  quantity. 

Samples  of  nitro-hydrocellulose,  wholly  soluble  in 
ether-alcohol,  of  nitration  as  high  as  12.6  to  12.7 
per  cent.,  were  obtained  by  nitrating  hydrocellulose 
in  the  acid  mixtures  I  was  employing  to  prepare 
directly  mixtures  of  insoluble  and  soluble  nitro-cellu- 
lose  from  cotton.  This  led  to  extended  series  of  trials 
of  powders,  of  both  the  accelerated  and  the  unaccel- 
erated  types,  containing  different  quantities  of  the  two 
varieties  of  nitro-hydrocelluloses  in  various  propor- 
tions, with  a  view  of  investigating  their  stability  and 
their  ballistic  properties. 

On  account  of  their  extreme  brittleness,  these  col- 
loid powders  proved  too  brusque,  and  experiments 
with  them  were  abandoned.  They  also  failed  in  cer- 
tain cases  to  develop  normal  stability. 

7. — The  observation  of  certain  remarkable  phenom- 
ena connected  with  the  effect  of  decrease  in  tempera- 
ture in  promoting  the  solution  and  colloidization  of 
certain  forms  of  nitro-cellulose  in  certain  solvents, — 
to  which  reference  is  made  in  detail  in  a  subsequent 
portion  of  this  work, — led  me  to  take  up  the  consider- 
ation of  temperature,  as  an  important  factor  in  the  con- 
trol of  the  character  and  degree  of  nitration.  I  con- 
ducted extended  series  of  experiments  in  which  cotton 
was  nitrated  in  various  acid  mixtures  at  temperatures 


36  SMOKELESS  POWDER 

ranging  between  o°  C.  and  80°  C.  The  result  of  these 
experiments  was  the  development  of  pyrocellulose, — a 
form  of  soluble  nitro-cellulose  of  high  nitration,  which, 
for  a  given  weight  of  its  substance,  converted  into 
colloid  grains  of  standard  dimensions  and  dried,  de- 
veloped, when  fired  from  the  standard  gun,  the  high- 
est muzzle  velocity,  as  compared  with  a  given  limiting 
bore  pressure. 

The  results  of  the  observations  in  this  regard  may 
be  briefly  summarized  as  follows : 

The  physical  and  chemical,  characteristics  of  prod- 
ucts of  nitration  are  subject  to  radical  modifications, 
through  variation  of  temperature  at  which  the  reac- 
tion is  conducted.  Increase  of  temperature  has  the 
effect  of  raising  the  nitration  of  both  the  soluble  and 
the  insoluble  varieties,  and  would  appear  also  to  in- 
crease the  percentage  of  the  soluble  component  in  a 
blend  of  the  soluble  and  insoluble  varieties.  The  heat 
employed  may  be  derived  from  two  sources:  (i)  that 
evolved  during  the  exothermic  reaction  of  the  nitra- 
tion of  cellulose;  (2)  that  which  is  supplied  from  ex- 
ternal sources  to  additionally  raise  the  temperature  of 
the  nitrating  mass.  If  the  temperature  of  the  nitrat- 
ing mass  be  raised  above  a  certain  point,  the  structure 
of  the  cellulose  is  attacked,  and  the  nitro-celluloses 
cease  to  form,  the  material  dissolving  in  the  acid,  with 
the  resultant  formation  of  nitro-substitution  bodies  of 
other  genera,  such  as  the  nitro-saccharoses;  or  else, 
direct  decomposition  of  the  nitrated  body  ensues, 
with  evolution  of  copious  fumes  of  nitric-oxide  gas. 
The  chemical  and  physical  phenomena  attending 


PROGRESSION  37 

both  the  decomposition  and  formation  of  nitre-cellu- 
loses are  largely  controlled  by  temperature.  Thus, 
the  explosive  force  of  gun-cotton  is  greatly  reduced 
by  freezing  the  latter.  Gun-cotton  saturated  with 
liquid  air  is  not  only  not  an  explosive,  but  is  practically 
a  non-combustible ;  while  non-nitrated  cotton  under 
similar  conditions  is  a  violent  explosive.* 

Again,  as  will  be  shown  hereafter,  the  extent  of  solu- 
bility of  certain  nitro-celluloses  in  certain  solvents  is 
a  function  of  the  temperature  at  which  the  solution  is 
undertaken ;  so  that  the  relative  quantities  of  the 
soluble  and  insoluble  constituents  in  a  mixture  of 
nitro-celluloses  formed  at  one  operation  may  depend 
upon  the  temperature  at  which  the  separation  of  the 
sub-constituents  is  effected. 

*  The  result  of  experiments  made  by  me  in  New  York  in  Octo- 
ber, 1899. 


CHAPTER   IV 

SOLUTIONS    OF    NITRO-CELLULOSE.      THEORY    OF 
THE  CELLULOSE   MOLECULE 

CELLULOSE  is  found  to  possess,  after  nitration,  a  re- 
markable property  that  unnitrated  cellulose  does  not 
possess:  it  dissolves  freely  in  a  number  of  liquids,  in 
which  it  is  not  soluble  in  the  unnitrated  state.  Of  these,  - 
the  solvents  ethyl  ether,  ethyl  alcohol,  ether-alcohol, 
and  acetone  are  of  special  interest,  both  from  their 
connection  with  the  manufacture  of  smokeless  powder, 
and  from  the  physical  and  chemical  bearings  of  their 
methods  of  effecting  solutions.  From  the  solutions 
the  nitro-cellulose  forms  with  them  it  may  be  precipi- 
tated by  the  addition  of  an  excess  of  water  or  other 
liquid  in  which  it  is  not  soluble,  in  a  flocculent  form; 
and  ultimately,  after  drying,  forms  a  pulverulent  mass. 
It  is  to  be  specially  remarked  that  the  nitro-cellulose 
cannot  be  recovered  in  its  original  cellular  state ;  the 
process  of  solution  has  destroyed  its  organic  structure, 
which  may  not  be  recovered  or  recreated. 

The  process  of  effecting  the  solution  of  the  nitro- 
cellulose may  be  regarded  as  preliminary  to  the  forma- 
tion of  the  colloid.  All  forms  of  nitro-cellulose  dis- 
solve freely  in  an  excess  of  those  solvents,  in  contact 
with  smaller  quantities  of  which  they  form  colloids 

33 


SOLUTIONS   OF  NITRO-CELLULOSE  39 

directly.  If  the  quantity  of  solvent  be  reduced  below 
a  certain  point  in  proportion  to  the  quantity  of  nitro- 
cellulose employed,  colloidization  ensues  without  pre- 
vious liquefaction ;  if  the  solvent  be  sufficient  in 
quantity  to  effect  liquefaction,  evaporation  of  excess 
of  solvent  must  precede  colloidization;  if  the  one  state 
can  be  produced,  the  possibility  of  forming  the  other 
may  be  predicated. 

The  line  between  solution  and  colloidization  is  not 
to  be  drawn  sharply ;  the  two  states  of  matter  merging 
into  one  another.  There  are,  however,  two  distinct 
sets  of  progressive  steps  or  series  of  physical  changes 
to  be  observed,  through  one  or  the  other  of  which 
these  bodies  pass  in  their  transformation  from  the 
liquid  to  the  solid  state,  and  which  may  be  expressed 
with  reference  to  their  progression  as  follows: 

First  series:  (a)  liquid;  (b)  jelly ;  (c)  elastic  mass; 
(d)  tough  colloid. 

Second  series  :  (a)  liquid  ;  (f)  slime ;  (c]  plastic  mass ; 
(d)  brittle  colloid. 

To  Series  I  belong  most  ether-alcohol  colloids;  to 
Series  II,  most  acetone  colloids. 

The  purpose  of  the  present  chapter  is  to  describe 
nitro-cellulose  solutions,  the  methods  of  forming  them, 
and  their  characteristics  apart  from  consideration  of 
their  colloidal  evaporated  residues;  and  to  present  in' 
relation  thereto  certain  theoretical  considerations 
throwing  light  upon  the  chemical  constitution  of  cel- 
lulose and  its  nitrates.  The  subjects  of  colloids,  their 
properties  and  methods  of  formation,  will  be  treated 
subsequently. 


40  SMOKELESS  POWDER 

A  discussion  of  the  solubility  of  nitro-celluloses  may 
best  be  prefaced  by  an  account  of  a  remarkable  prop- 
erty of  soluble  nitro-celluloses  in  general,  especially 
characteristic  of  pyrocellulose  and  of  those  forms  of 
nitro-hydrocellulose  soluble  in  ether-alcohol;  viz., 
the  direct  solubility  of  these  bodies  in  the  solvent  ether  * 
when  subjected  to  the  influence  of  cold. 

In  August,  1896,  I  conducted  a  series  of  experi- 
ments with  soluble  nitro-hydrocellulose  of  very  high 
nitration,  to  determine  its  adaptability  for  conversion 
into  smokeless  powder;  this  material,  colloided  in 
ether-alcohol  and  dried,  had  given  promise  of  value  as 
a  progressive  explosive. 

Upon  a  very  warm  Sunday  afternoon,  I  visited  a 
dry-house  in  which  a  small  tray  of  soluble  nitro-hydro- 
cellulose, of  high  nitration  (N  12.4-!-),  was  exposed 
to  a  moderate  drying  temperature.  Removing  about 
one  gram  of  the  amorphous  gray  powder  from  the  dry- 
ing-tray, I  introduced  it  into  a  tfest-tube,  which  I 
tightly  closed  with  a  rubber  stopper  to  prevent  the 
absorption  of  moisture.  I  then  visited  the  chemical 
laboratory  and  partly  filled  the  tube  with  what  I  sup- 
posed to  be  ether-alcohol.  To  my  disappointment 
the  precipitate  did  not  dissolve.  Upon  agitation,  it 
diffused  itself  throughout  the  liquid,  but  rapidly  settled 
to  the  bottom,  in  its  original  pulverulent  form,  when 
brought  to  rest.  I  at  first  attributed  this  behavior 
to  excessive  nitration,  believing  the  material  to  con- 

*When  "  ether  "  and  "  alcohol "  are  referred  to  without  quali- 
fication, they  are  intended  to  designate  ethyl  ether  and  ethyl 
alcohol. 


SOLUTIONS    OP   NT1RO-CELLULOSE  4! 

sist  of  insoluble  instead  of  soluble  nitro  cellulose.  Hav- 
ing observed,  however,  during  the  previous  winter  that 
certain  of  the  insoluble  nitro-hydrocelluloses  appeared 
to  exhibit  a  tendency  to  enter  into  solution  upon  ex- 
posure to  cold  (a  portion  of  the  precipitate  appearing 
to  rise  in  the  tube,  like  a  jelly,  under  the  influence 
of  cold),  it  occurred  to  me  to  try  the  effect  of  a  salt- 
and-ice  freezing  mixture  upon  the  tube  and  its  con- 
tents. I  therefore  mixed  a  small  quantity  of  salt  and 
ice  in  a  beaker,  into  which  I  introduced  the  tube  in  a 
central  vertical  position.  To  my  great  satisfaction, 
the  whole  of  the  precipitate  went  rapidly  into  solution, 
forming  a  yellowish-brown,  mobile  fluid. 

While  considering  the  phenomenon  that  I  had  wit- 
nessed, I  remained  seated  at  my  desk,  holding  the 
test-tube  enclosed  within  the  palm  of  my  hand.  Sud- 
denly I  noticed  that,  although  I  had  shifted  the  tube 
into  the  inverted  position  (cork  downwards),  yet  the 
contents,  masked  by  my  hand,  had  not  observed  the 
law  of  liquid  flow,  for  the  lower  uncovered  end  of  the 
test-tube,  which  extended  downwards,  was  empty. 
Carefully  opening  my  hand,  I  was  surprised  to  find 
that  the  contents  of  the  tube  had  condensed  into  a 
dense  jelly,  which  remained  fixed  in  the  upper  part  of 
the  tube.  I  re-introduced  the  tube  into  the  freezing 
mixture ;  its  contents  liquefied  as  before,  being  trans- 
formed into  a  liquid  as  mobile  as  maple-syrup ;  re- 
moval from  the  source  of  cold  and  immersion  in  water 
heated  to  about  100°  F.  (38°  C.),  or  holding  in  the 
palm  of  the  hand,  sufficed  to  cause  the  liquid  to  con- 
geal. 


42  SMOKELESS  POWDER 

The  phenomenon  above  described  related  to  the 
behavior  of  soluble  nitro-hydrocellulose  in  the  pres- 
ence of  an  excess  of  solvent  (ether)  when  contained  in 
a  sealed  vessel  which  is  exposed  successively  to  differ- 
ent temperatures;  removal  of  the  cork  with  subsequent 
evaporation  of  the  solvent  results  in  the  formation  of 
a  solid  colloid  residue,  non-liquefiable  upon  variation 
of  temperature. 

After  producing  the  results  above  described,  I  next 
endeavored  to  duplicate  them.  To  my  surprise,  the 
soluble  nitro-cellulose,  which  I  supposed  the  same  as 
that  I  employed  the  day  before,  promptly  went  into 
solution  in  ether-alcohol  at  a  temperature  of  about 
70°  F.  Investigation  led  to  the  discovery  of  an  un- 
fortunate interchange  of  trays  in  the  dry-house,  which 
rendered  it  impossible  to  repeat  with  certainty  the 
experiment  cited.  There  was,  therefore,  but  one 
mode  of  procedure  left — to  select  sample  lots  from  all 
the  trays,  one  of  which  must  represent  the  lot  origin- 
ally taken,  and  experiment  with  them  in  the  presence 
of  ether-alcohol.  Still  I  was  unable  to  obtain  the 
original  results.  It  next  occurred  to  me  that  I  might 
have  employed  by  mistake  some  solvent  other  than 
ether-alcohol,  and  as  the  result  of  a  day's  experiment- 
ing, I  found  that  phenomena  identical  with  those 
originally  developed  could  be  obtained  with  soluble 
nitro-hydrocelluloses  using  ethyl  ether  as  a  solvent. 

Experimenting  subsequently,  1899-1900,  to  ascer- 
tain whether  the  above  phenomena  were  peculiar  to 
nitro-hydrocelluloses,  or  whether  they  were  character- 
istic of  all  soluble  nitro-celluloses,  I  found; 


SOLUTIONS   OF  NITRO-CELLULOSE  43 

I. — That  pyrocellulose  could  be  readily  dissolved 
in  ether  upon  application  of  cold. 

2. — That  all  soluble  nitre-celluloses  acted  similarly 
in  presence  of  an  excess  of  ether,  but  that  some  were 
more  readily  disintegrated  by  ether  upon  application  of 
cold  than  others. 

3. — That  if  the  necessary  degree  of  cold  were  de- 
veloped, soluble  nitro-celluloses  were  not  only  soluble 
to  any  desired  extent  in  ether,  but  that  they  could  be 
colloided  directly  therein,  without  recourse  to  lique- 
faction. 

4. — That  the  addition  of  a  few  drops  of  alcohol  in 
difficult  cases  appeared  to  be  equivalent  to  a  lowering 
of  temperature,  i.e.,  it  rendered  a  given  soluble  nitro- 
cellulose more  soluble  in  ether,  in  the  presence  of  a 
given  degree  of  cold,  than  it  otherwise  would  have 
been. 

The  problem  of  nitro-cellulose  solution  may  be  ap- 
propriately prefaced  with  the  query :  Why  are  certain 
forms  of  soluble  nitro-cellulose  readily  soluble  at  ordi- 
nary atmospheric  temperatures  in  a  compound  of  two 
parts  by  weight  of  ethyl  ether  with  one  part  by  weight 
of  ethyl  alcohol;  whereas,  the  said  forms  of  nitro-cel- 
lulose are  not  soluble  to  any  appreciable  extent,  at 
ordinary  atmospheric  temperatures,  in  an  excess  of 
either  ethyl  ether  or  ethyl  alcohol,  when  either  is 
employed  alone  as  a  solvent?  The  point  emphasized 
is,  why  should  the  single  material,  soluble  nitro-cellu- 
lose, prove  more  soluble  in  a  mixture  of  two  solvents 
than  in  either  solvent  separately? 

If  one-tenth  of  a  gram  of  soluble  nitro-cellulose  be 


44  SMOKELESS  POWDER 

placed  in  a  test-tube  and  covered  with,  say,  25  c.c.  of 
ethyl  alcohol,  and  the  test-tube  be  corked  and  then 
violently  agitated,  it  will  be  found  that  solution  will 
not  ensue,  but  that  the  soluble  nitro-cellulose  will  (if 
pulped)  gradually  settle  to  the  bottom  after  the  tube 
is  brought  to  rest,  or  else  remain  suspended  in  an 
undissolved  state  in  the  liquid.  Similarly,  the  same 
quantity  of  nitro-cellulose  will  remain  undissolved  in, 
say,  twice  the  same  quantity  of  ether  under  similar 
treatment.  If,  however,  the  contents  of  the  two  tubes 
be  combined,  the  soluble  nitro-cellulose  will  promptly 
go  into  solution  in  the  mixture  of  the  two  solvents. 

Solubility  in  ether  and  solubility  in  alcohol  must  be 
touched  upon  before  proceeding  to  the  question  of 
solubility  in  the  compound  solvent.  It  is  known  that 
certain  nitro-celluloses  of  low  nitration  are  soluble  in 
ethyl  alcohol.  To  this  Vieille  and  Mendeleef  attest, 
and  the  latter  recommends  that  this  fact  be  taken 
advantage  of  to  remove  traces  of  nitro-celluloses  of 
low  nitration  from  those  of  higher  nitration,  the 
higher  soluble  nitro-celluloses  not  being  soluble  in 
alcohol,  at  least  not  at  ordinary  temperatures. 

If  it  happened  that  the  soluble  nitro-cellulose  dis- 
solved with  the  same  ease  in  warm  alcohol  that  it  does 
in  cold  ether,  the  action  of  the  compound  solvent 
could  be  accounted  for  on  simple  physical  grounds. 
A  mixture  of  the  two  solvents  might  so  balance  differ- 
ences of  temperature  as  to  effect  solution  at  some  tem- 
perature that  represented  a  mean  proportional  to  the 
percentage  of  each  solvent  in  the  mixture.  The  at- 
tempt was  made,  therefore,  to  dissolve  pyrocellulose 


SOLUTIONS  OF  NITRO-CELLULOSE  45 

in  alcohol  (95 -per  cent.)  heated  to  near  its  boiling 
point,  but  proved  unsuccessful.  On  the  contrary, 
the  tendency  was  rather  away  from  than  toward  solu- 
tion. This  theory  was,  therefore,  untenable. 

Having  alluded  briefly  to  the  effect  upon  soluble 
nitro-cellulose  of  the  individual  solvents,  (i)  ethyl 
alcohol,  and  (2)  ethyl  ether,  the  solubility  in  the  com- 
pound ether-alcohol  solvent  may  next  be  considered. 

In  their  work,  "  Cellulose  "  (London:  Longmans, 
Green  &  Co.),  Cross  and  Bevan,  referring  to  cellulose 
and  its  hydration,  state  (p.  1 1) : 

11  According  to  modern  views  on  the  subject  of  solu- 
tion generally,  and  the  solution  of  colloids  in  particu- 
lar, the  lines  drawn  by  the  older  investigators  of  these 
phenomena  are  of  arbitrary  value  ;  gelatinization  being 
expressed  as  a  continuous  series  of  hydrations  between 
the  extreme  conditions  of  solid  on  the  one  side  and 
aqueous  solution  on  the  other." 

In  their  physical  forms  the  solutions  of  nitro-cellu- 
loses  in  ether  and  ether-alcohol  present  striking  analo- 
gies to  the  hydrated  and  gelatinized  forms  of  cellulose 
itself.  If,  as  stated,  the  gelatinized  or  hydrated  form 
may  be  regarded  as  a  continuous  series  of  hydrations 
of  cellulose,  then  the  colloids  can  be  regarded  as  what 
may  be  termed  a  continuous  series  of  etherizations  or 
alcoholizations  of  nitro-cellulose.  In  this  manner  we 
may  establish  an  analogy  in  point  of  behavior  between 
cellulose  in  the  presence  of  water  and  nitro-cellulose  in 
the  presence  of  ether,  alcohol,  and  ether-alcohol. 

Referring  again  to  Cross  and  Bevan,  "Cellulose," 
we  find  (pp.  4  and  5): 


46  SMOKELESS  POWDER 

"All  vegetable  structures  in  the  air-dry  condition 
retain  a  certain  proportion  of  water,  or  hygroscopic 
moisture,  as  it  is  termed,  which  is  readily  driven  off  at 
I OO°  (C.),  but  reabsorbed  on  exposure  to  the  atmos- 
phere under  ordinary  atmospheric  conditions." 

"  The  phenomenon  is  definitely  related  to  the  pres- 
ence of  OH  groups  in  the  cellulose  molecule,  for  in 
proportion  as  these  are  suppressed  by  combination 
(with  negative  radicles  to  form  the  cellulose  esters)  the 
products  exhibit  decreasing  attractions  for  atmospheric 
moisture.  It  is  to  be  noted  that  some  of  these  syn- 
thetical derivatives  are  formed  with  only  slight  modifi- 
cations of  the  external  or  visible  structure  of  the  cellu- 
lose, of  which,  therefore,  the  phenomenon  in  question 
is  again  shown  to  be  independent." 

In  parallel  to  this  we  may  state: 

The  series  of  the  cellulose  esters  known  as  the  nitro- 
celluloses  exhibit  at  ordinary  atmospheric  tempera- 
tures, with  ether  and  alcohol,  effects  similar  to  those 
of  cellulose  with  water  in  what  relates  to,  (i)  hygro- 
copic  moisture,  and  (2)  gelatinization. 

In  relation  to  the  effect  of  alkalies  on  concentrated 
solutions — and  this  is  of  primary  importance  in  connec- 
tion with  our  subject — Cross  and  Bevan  state  (p.  23)  : 

"  Cold  solutions  of  the  alkaline  hydrates  of  a  certain 
concentration  exert  a  remarkable  effect  upon  the  cellu- 
loses. Solution  of  sodium  hydrate,  at  strengths  ex- 
ceeding 10  per  cent.  NaaO,  when  brought  into  contact 
with  the  cotton  fibre,  at  the  ordinary  temperature,  in- 
stantly changes  its  structural  features,  i.e.,  from  a  flat- 
tened riband,  with  a  large  central  canal,  produces  a 


SOLUTIONS   OF  NITRO-CELLULOSE  47 

thick  cylinder  with  the  canal  more  or  less  obliterated. 
These  effects  in  the  mass,  e.g.,  in  cotton  cloth,  are 
seen  in  a  considerable  shrinkage  of  length  and  width, 
with  corresponding  thickening,  the  fabric  becoming 
translucent  at  the  same  time.  The  results  are  due  to 
a  definite  reaction  between  the  cellulose  and  the  alka- 
line hydrates,  in  the  molecular  ratio  CiaHaoO,0:  2NaOH, 
accompanied  by  combination  with  water  (hydration). 
The  compound  of  the  cellulose  and  alkali  which  is 
formed  is  decomposed  on  washing  with  water,  the 
alkali  being  recovered  unchanged,  the  cellulose  ap- 
pearing in  a  modified  form,  viz.,  as  the  hydrate 
CiaHaoO10.HaO.  By  treatment  with  alcohol,  on  the 
other  hand,  one  half  of  the  alkali  is  removed  in  solu- 
tion, the  reacting  groups  remaining  associated  in  the 
ratio  C,aHaoO,0  :  NaOH.  The  reaction  is  known  as 
that  of  mercerization,  after  the  name  of  Mercer,  by 
whom  it  was  discovered  and  exhaustively  investigated. 
Although,  however,  it  aroused  a  good  deal  of  attention 
at  the  time  of  its  discovery,  it  remained  for  thirty  years 
an  isolated  observation,  i.e.,  practically  undeveloped. 
Recently,  however,  the  alkali  cellulose  has  been  made 
the  starting  point  of  two  series  of  synthetical  deriva- 
tives of  cellulose,  which  must  be  briefly  described." 

"  From  the  points  established  by  Mercer  in  connec- 
tion with  this  reaction,  the  following  may  be  further 
noted : 

"At  ordinary  temperatures  a  lye  of  1.225-1.275 
sp.  gr.  effects  'mercerization'  in  a  few  minutes; 
weaker  liquors  produce  the  result  on  longer  exposure, 
the  duration  of  exposure  necessary  being  inversely 


48  SMOKELESS  POWDER 

as  the  concentration.  Reduction  of  temperature  pro- 
duces, within  certain  limits,  the  same  effect  as  in- 
creased concentration.  The  addition  of  zinc  oxide 
(hydrate)  to  the  alkaline  lye  also  increases  its  activity. 
Caustic-soda  solution  of  i.ioo  sp.  gr.,  which  has  only 
a  feeble  'mercerizing*  action,  is  rendered  active  by 
the  addition  of  the  oxide  in  the  molecular  proportion 
Zn(OH)a:4NaOH." 

Two  points  in  the  above  merit  special  attention  in 
connection  with  our  subject.  They  are : 

I. — The  removal  of  one-half  of  the  alkali  on  treat- 
ment with  alcohol,  the  reacting  groups  remaining  as- 
sociated in  the  ratio  CiaH90O]0  :  NaOH. 

2. — The  acceleration,  on  exposure  to  a  lye  of 
1.225-1.275  sp.  gr.,  of  the  process  of  "  mercerization  " 
by  reduction  of  temperature.  Here  is  presented  an 
analogy  to  the  increased  solubility  of  nitro-cellulose  in 
ether  and  ether-alcohol  upon  application  of  cold. 

In  referring  to  the  production  of  cellulose  thio- 
carbonates  and  to  the  quantitative  regeneration  of 
cellulose  from  solution  as  thiocarbonate,  Cross  and 
Bevan  state  (pp.  29-31): 

4 'The  occurrence  of  this  reaction,  under  what  may 
be  regarded  as  the  normal  conditions,  proves  the 
presence  in  cellulose  of  OH  groups  of  distinctly  alco- 
holic function.  The  product  is  especially  interesting 
as  the  first  instance  of  the  synthesis  of  a  soluble  cellu- 
lose derivative — i.e.,  soluble  in  water — by  a  reaction 
characteristic  of  the  alcohols  generally.  The  actual 
dissolution  of  the  cellulose  under  this  reaction  we  can- 
not attempt  to  explain,  so  long  as  our  views  of  the 


SOLUTIONS  OF  NITRO-CELLULOSE  49 

general  phenomena  of  solution  are  only  hypotheses. 
There  is  this  feature,  however,  common  to  all  pro- 
cesses hitherto  described,  for  producing  an  aqueous 
solution  of  cellulose  (i.e.,  a  cellulose  derivative),  viz., 
that  the  solvent  has  a  saline  character.  It  appears, 
in  fact,  that  cellulose  yields  only  under  the  simulta- 
neous strain  of  acid  and  basic  groups,  and  therefore 
we  may  assume  that  the  OH  groups  in  cellulose  are 
of  similarly  opposite  function.  In  the  case  of  the 
zinc-chloride  solvents  there  cannot  be  any  other  de- 
termining cause,  and  the  soluble  products  may  be  re- 
garded as  analogous  to  the  double  salts.  The  reten- 
tion of  the  zinc  oxide  by  the  cellulose,  when  precipi- 
tated by  water,  is  an  additional  evidence  of  the  pres- 
ence of  acidic  OH  groups;  and  conversely,  the  much 
more  rapid  action  of  the  zinc  chloride  in  presence  of 
hydrochloric  acid  indicates  the  basicity  of  the  mole- 
cule, i.e.,  of  certain  of  its  OH  groups.  On  the  other 
hand,  in  both  the  cuprammonium  and  thiocarbonate 
processes  there  may  be  a  disturbance  of  the  oxygen 
equilibrium  of  the  molecule;  and  although  there  is  no 
evidence  that  the  cellulose  regenerated  from  these 
solutions  respectively  is  oxidized  in  the  one  case  or 
deoxidized  in  the  other,  it  is  quite  possible  that  tem- 
porary migration  of  oxygen  or  hydrogen  might  be 
determined,  and  contribute  to  the  hydration  and  ulti- 
mate solution  of  the  cellulose.  But,  apart  from  hy- 
potheses, we  may  lay  stress  on  the  fact  that  these  pro- 
cesses have  the  common  feature  of  attacking  the  cellu- 
lose in  the  two  directions  corresponding  with  those  of 
electrolytic  strain ;  and  it  is  on  many  grounds  prob- 


$O  SMOKELESS  POWDER 

able   that   the   connection   will  prove  casual   and  not 
merely  incidental."  * 

It  is  the  feature  of  double  attack  upon  the  cellulose 
that  suggests  the  cause  of  the  increased  solubility  of 
the  nitro-cellulose  in  the  compound  ether-alcohol  sol- 
vent, as  compared  with  its  relative  solubility  in  the 
ether  and  alcohol  separately.  In  the  case  of  the 
"  mercerized  "  cellulose  we  observe  that  a  removal  of 
one-half  the  alkali  is  effected  by  the  alcohol  treat- 
ment. The  reaction  of  the  alcohol  here  relates  to  the 
basic  OH  groups,  the  alkali  appearing  to  be  retained 
as  a  base  in  the  groups  of  acid  reaction.  A  lower 
temperature  facilitates  the  "  mercerization  "  process; 
this  may  be  interpreted  into  the  statement  that  raising 
the  temperature  of  the  molcule  beyond  a  certain  point 
retards  the  process.  So,  in  the  case  of  the  increased 
solubility  of  soluble  nitro-cellulose  in  ethyl  alcohol  at 
low  temperatures,  the  employment  of  artifical  cold 
accelerates  the  process  of  solution.  We  may  here  as- 
sume that  the  material,  from  its  dual  character,  is 
under  an  electrolytic  strain,  from  which  it  is  removed 
by  application  of  cold  (abstraction  of  heat) ;  the  alco- 


*  Referring  to  the  character  of  the  regenerated  cellulose  in 
comparison  with  the  original  material,  Cross  and  Bevan  state, 
inter  al.  : 

"  (i)  Its  hygroscopic  moisture,  or  water  of  condition,  is  some  3  to 
4  per  cent,  higher,  viz.,  from  9  to  10.5  per  cent. 

"  (2)  Empirical  composition.  The  mean  results  of  analysis  show 
C  —  43-3  Per  cent.,  H  —  6.4  per  cent.,  which  are  expressed  by  the 
empirical  formula  4C8HioO6.H2O." 

It  will  be  observed  that  the  regenerated  material  is  an  amor- 
phous hydrocellulose. 


SOLUTIONS   OP  NITRO-CELLULOSE  5 1 

hoi  then  attacks  and  dissolves  the  basic  OH  groups; 
the  structure  of  the  cellulose  is  destroyed ;  the  acid 
groups  yield  subsequently  and  enter  into  solution,  to 
effect  which  there  may  occur,  as  suggested  by  Cross 
and  Bevan  for  cellulose,  a  temporary  transfer,  within 
the  molecule  of  nitro-cellulose,  of  hydrogen  and  oxy- 
gen ;  and  the  whole  substance  finally  yields  to  alco- 
holization in  a  manner  analogous  to  that  by  which 
cellulose  itself  yields  to  hydration. 

Similarly,  for  the  increased  solubility  of  soluble 
nitro-cellulose  in  ethyl  ether  at  low  temperatures,  the 
employment  of  artificial  cold  accelerates  the  process 
of  solution.  The  ether  dissolves  the  acid  OH  groups 
(in  contradistinction  to  the  action  of  the  alcohol, 
which  attacks  the  basic  OH  groups);  the  structure  of 
the  cellulose  is  destroyed ;  the  basic  groups  yield  sub- 
sequently, to  effect  which  there  occurs  a  transfer  of 
hydrogen  and  oxygen  within  the  molecule  in  a  direc- 
tion opposite  to  that  in  which  it  occurs  in  the  previ- 
ous case,  and  the  whole  substance  finally  yields  to 
etherization  in  a  manner  similar  to  that  by  which  cel- 
lulose itself  yields  to  hydration. 

As  bearing  upon  the  theory  it  may  be  remarked  that 
the  two  solvents,  ethyl  alcohol  and  ethyl  ether,  differ 
by  H-O-H,  since  ether,  (C,H6),O,  +  HaO  =  alcohol, 
2C,H60. 

In  the  case  of  the  mixed  ether-alcohol  solvent  we 
subject  the  cellulose  in  the  one  operation  to  the  double 
tendency  to  disintegration.  The  necessity  for  the 
application  of  cold  (or  the  absorption  of  heat)  to  ef- 
fect the  necessary  arrangement  of  the  H-O-H  groups, 


5  2  SMOKELESS  POWDER 

as  they  may  be  styled,  i.e.,  to  strain  them  into  basic 
and  acid  relations,  is  no  longer  required,  for  the  double 
attack  in  two  directions,  corresponding  to  those  of 
electrolytic  strain,  is  provided  for  by  the  parallel  double 
composition  of  the  ether-alcohol  solvent. 

There  is  reason  for  supposing  that  the  above-de- 
scribed reaction  is  not  limited  in  its  occurrence  to 
forms  of  soluble  nitro-cellulose  alone,  but  that  it 
obtains  equally  for  the  insoluble  varieties.  If  the 
theory  be  correct,  then  insoluble  nitro-cellulose  should 
be  soluble  in  ether.  Macnab  has  shown  that  insoluble 
nitro-cellulose  dissolves  in  ether-alcohol  at  a  very  low 
temperature.* 

In  the  fall  of  1899,  the  time  that  liquid  air  first  be- 
came readily  obtainable  in  quantity  in  New  York,  I 
decided  to  check  Macnab's  experiment  by  employing 
this  material  as  a  refrigerant;  also  (i)  to  experiment 
with  a  view  of  ascertaining  whether  insoluble  nitro- 
cellulose of  very  high  nitration  in  its  unpulped  fibrous 
form, — the  form  in  which  it  might  be  supposed  to 
oppose  a  maximum  resistance  to  the  disintegrating 
action  of  solvents, — would  not  actually  go  into  solu- 
tion in  ethyl  ether  alone  under  influence  of  extreme 
cold ;  and  (2)  to  determine  how  far  nitro-cellulose  is 
soluble  in  absolute  ethyl  alcohol.  The  ether  em- 
ployed in  these  experiments  was  Squibbs',  C.P.,  for 

*  See  experiments  cited  by  Guttmann  in  his  article  "  Manufac- 
ture of  Explosives,"  published  in  the  Journal  of  the    Society  of 
Chemical  Industry,  London,  June  30,  1894  ;    also   p.  404  appendix  v 
to  his  recently  published  work,  "  Manufacture  of  Explosives," 
London:  Macmillan. 


SOLUTIONS   OF  NITRO-CELLULOSE  53 

anesthesia;  the  insoluble  nitrocellulose  was  gun- 
cotton  of  high  nitration  (N  =  13.4+)  and  purity,  in 
the  unpulped  state. 

The  solvent  employed  in  the  alcohol  experiments 
was  absolute  ethyl  alcohol ;  the  nitro-celluloses  were 

(1)  soluble  nitro-hydrocellulose  of  nitration,  N  11.4$; 

(2)  soluble  nitro-hydrocellulose  of  N  12. 6$;  (3)  pulped 
pyrocellulose,  N  12. 42$;  and  (4)  unpulped  gun-cotton 
of  high  nitration,  N  13.4$. 

Experiment  I. — I  placed  about  one-tenth  gram  of 
gun-cotton  in  a  test-tube,  poured  over  it  25  c.c.  of  2  :i 
ether-alcohol,  tightly  closed  the  tube  with  a  rubber 
stopper  and  immersed  it  in  a  vessel  containing  about 
750  c.c.  of  liquid  air.  When  the  contents  of  the  tube 
became  sufficiently  cooled,  the  gun-cotton  went  read- 
ily into  solution,  forming  a  clear  mobile  liquid  of  a 
honey-yellow  color.  I  found  that  the  gun-cotton  re- 
mained in  the  colloid  form  after  the  removal  of  the 
tube  from  the  liquid  and  the  subsequent  heating  of  its 
contents  to  the  temperature  of  the  atmosphere.  On 
removing  the  tube  from  the  liquid-air  bath,  uncorking 
and  allowing  the  contents  to  evaporate,  the  residue 
formed  a  tough,  homogeneous  amber-colored  film. 

Experiment  II. — Having  succeeded  readily  in  col- 
loiding  insoluble  nitro-cellulose  in  ether-alcohol,  I  next 
decided  to  ascertain  whether  it  were  possible  to  col- 
loid it  in  ether  alone.  I  placed  one-tenth  gram  of  the 
gun-cotton  in  a  test-tube,  poured  over  it  about  25  c.c. 
of  ether,  tightly  closed  the  tube  and  immersed  it  in 
the  same  quantity  of  liquid  air  as  before. 

Upon    sufficiently  reducing    the    temperature,   the 


54  SMOKELESS  POWDER 

contents  of  the  tube  became  solid  and  the  ether  froze 
into  a  snow-white  mass.  On  removing  the  tube  from 
the  cold  and  allowing  the  ether  to  melt,  I  found  that 
the  gun-cotton  had  disintegrated  and  gone  into  solu- 
tion, forming  a  mobile  slightly  clouded  liquid  with  a 
yellowish  tinge.  The  gun-cotton  remained  in  solution 
after  the  withdrawal  of  the  tube  from  the  liquid  air 
and  the  subsequent  heating  of  its  contents  to  the 
temperature  of  the  atmosphere.  On  removing  the 
tube  from  the  liquid-air  bath,  uncorking  and  allowing 
its  contents  to  evaporate,  the  residue  formed  a  tough, 
homogeneous,  slightly  yellowish  colloid. 

Experiment  III. — About  one-tenth  gram  of  each 
of  the  above-mentioned  series  of  nitro-celluloses  was 
each  placed  in  a  separate  test-tube  and  each  had 
poured  over  it  about  25  c.c.  of  absolute  ethyl  alcohol. 
The  tubes  thus  partly  filled  were  closed  tightly  with 
rubber  stoppers,  immersed  in  liquid  air  (for  about 
two-thirds  of  their  lengths),  and  allowed  to  remain 
therein  for  five  minutes.* 

The  contents  of  each  tube  froze  in  about  half  a 
minute  and  the  rest  of  the  time  the  liquid  air  was 
acting  upon  the  frozen  contents.  On  removing  the 
tube  containing  the  gun-cotton  from  the  bath  and 
allowing  its  contents  to  melt,  the  gun-cotton  was,  to 

*  The  liquid  air  for  these  experiments  was  very  kindly  fur- 
nished me  by  Messrs.  Vandivert  and  Gardenhire,  of  32  Broadway, 
New  York,  pioneers  in  the  development  of  liquid  air  in  the  United 
States.  I  am  also  indebted  to  Mr.  M.  Burger,  president  of  the 
company,  for  his  kindness;  and  especially  to  Mr.  O.  Ostergren 
of  New  York,*  one  of  the  original  experimenters  and  developers 
of  the  commercial  manufacture  of  liquid  ain 


SOLUTIONS   OF  NITRO-CELLULOSE  55 

all  appearances,  unaltered.  This  showed  that,  whether 
or  not  the  fibre  of  the  cotton  had  been  attacked,  it 
was  not  affected  to  the  same  extent  by  the  ethyl 
alcohol  as  it  was  by  the  ethyl  ether,  which,  as  pre- 
viously shown,  destroyed  the  fibre  of  the  gun-cotton, 
causing  it  to  go  into  solution. 

The  sample  of  pyrocellulose  and  the  two  small  lots  of 
nitro-hydrocellulose  in  the  other  tubes  were  found  to 
have  gone  into  solution  in  the  ethyl  alcohol,  through 
the  action  of  the  cold,  the  former  affording  a  jelly- 
like  straw-colored  colloid ;  the  two  latter,  the  usual 
brownish-yellow  colloids. 

We  may  now  call  attention  in  parallel  to  the  follow- 
ing remarkable  reactions ; 

I. — That  nitro-celluloses  dissolve  in  ethyl  ether 
under  the  influence  of  intense  cold. 

2. — That  nitro-celluloses,  with  the  apparent  excep- 
tion of  the  highly  nitrated  insoluble  variety  (this  will 
be  further  experimented  with  later,  in  the  presence  of 
extreme  cold)  dissolve  in  ethyl  alcohol  under  the  in- 
fluence of  intense  cold. 

3. — That  the  so-called  soluble  forms  of  nitro-cellu- 
lose  of  mean  and  low  nitrations  go  into  solution  in  a 
mixture  of  ethyl  ether  and  ethyl  alcohol  at  ordinary 
atmospheric  temperatures. 

In   connection  with   the  above   may  be  mentioned : 

(a)  That  the  various  forms  of  nitro-celluloses  seem 
more  readily  soluble  in  ethyl  ether  than  in  ethyl  alcohol. 

(b  That  a  mixture  of  two  volumes  of  ethyl  ether 
to  one  of  ethyl  alcohol  seems  to  extract  at  ordinary 
atmospheric  temperatures  the  greatest  quantity  of 


56  SMOKELESS    POWDER 

soluble  constituents  from  a  mixture  of  the  two  forms 
of  nitro-cellulose  (soluble  and  insoluble  as  formed  by 
one  dipping  of  cotton.) 

It  now  remains  to  consider  the  theory  of  compo- 
sition of  cellulose  and  nitro-cellulose  from  the  chemical 
standpoint.  In  this  connection  it  is  necessary,  first  of 
all,  to  emphasize  the  fact  of  the  similarity  in  compo- 
sition of  the  cellulose  and  the  nitro-cellulose  molecule. 
The  latter  is  formed  from  the  former  by  the  substitu- 
tion, for  a  certain  number  of  replaceable  hydrogen 
atoms,  of  the  same  number  of  equivalents  of  nitryl — 
NO,.  The  effect  of  the  introduction  of  nitryl  into  the 
substance  of  the  cellulose  is  an  apparent  weakening 
of  the  stability  of  the  latter,  rendering  it  susceptible 
of  decomposition  in  a  number  of  additional  ways,  and 
making  actual  tendencies  to  decomposition,  traces  of 
which  exist  in  the  original  mate-rial,  but  which  are  held 
in  control  by  stronger  counteracting  tendencies  derived 
from  other  sources. 

For  the  sake  of  simplicity  the  formulae  presented  in 
what  follows  will  be  those  of  cellulose.  It  is  to  be 
understood  that  whenever  questions  arise  referring 
directly  to  nitro-cellulose,  such  as  solubility  in  ether 
or  ether-alcohol,  the  cellulose  molecule  as  presented  is 
to  be  considered  as  tacitly  representing  nitro-cellulose, 
without  actual  expression  of  the  substitution  of  NO, 
in  the  replaceable  hydrogen  atoms. 

Bearing  the  above  in  mind,  the  following  additional 
facts  may  be  taken  advantage  of  in  formulating  a 
theory  of  the  composition  of  the  cellulose  and  the 
nitro-cellulose  molecule ; 


SOLUTIONS   OF  NITRO-CELLULOSE  S7 

I. — The  two  solvents  of  soluble  nitro-cellulose,  ethyl 
ether  and  ethyl  alcohol,  differ  in  composition  by  H-O— 
H.  Like  HaO,  they  may  be  written  (CaH5)aO  and 
C,H.O  or  CaHB.O.H. 

2. — Cellulose,  CiaHaoO10,  is  transformed  by  treatment 
with  alkali  in  aqueous  solution  into  CiaH20O10.2NaOH. 

3.  By  subsequent  treatment  with  water  it  is  con- 
verted into  cellulose  hydrate,  CiaH90.O10.HaO. 

4. — By  treating  C^HjD^NaOH  with  alcohol, 
CaH6O,  the  former  is  converted  into  the  mercerized 
form,  C,,HaoO10.NaOH,  with  half  the  alkali  removed. 

To  account  for  the  occurrence  of  reactions  (2)  and 
(3),  the  composition  of  the  cellulose  molecule  is 
regarded  as  doubled,  i.e.,  raised  from  C,H,0O6  to 
C,aHaoO10.  (4)  is  of  especial  importance  and  interest,  as 
it  exhibits  the  action  of  alcohol  upon  non-nitrated  cel- 
lulose; establishing  a  basis  for  the  assumption  that  the 
action  of  the  double  ether-alcohol  solvent  upon  nitro- 
cellulose is  based  upon  the  original  composition  of 
cellulose  itself. 

Assuming  a  duality  of  composition  as  indicated  (i) 
by  its  basic  and  acid  reactions;  (2)  by  its  greater  solu- 
bility in  the  compound  solvent;  (3)  by  the  H-O-H 
difference  of  the  components  of  the  original  compound 
s6lvent ;  and  (4)  by  the  creation  and  absorption  of  the 
H-O-H  groups  in  the  formation  of  cellulose  hy- 
drates and  alkaline  compounds,  we  may  proceed  as 
follows : 

If  alcohol  is  capable  of  effecting  the  solution  of  a 
nitro-cellulose,  it  must  effect  the  solution  of  both  its 
components  or  resolve  itself  into  two  sub-components, 


58  SMOKELESS   POWDER 

each  reacting  on  one  sub-component  of  the  nitro-cel- 
lulose,  in  order  that  it  may  effect  the  solution  of  the 
whole.  Under  the  latter  assumption,  we  may  con- 
sider alcohol,  C,H6O,  as  having  the  composition 

H  H 


c 
|     H  H/  | 

H  H 

which  may  be  divided  into 

H  H 


and 

H  H'    | 

H  H 

Similarly,  we  may  regard  ethyl  ether,  (C2HB),O,  as 
having  the  composition 

H  H 

I  I 

H—  C—    O  —  C—  H 

I  I 

H—  C—  HH—  C—  H 

I  I 

H  H 

capable  of  dividing  into 

H  H 

H—  C—  —  O—  C-H 

|  and  | 

H—  C—  H  H—  C-H 


SOLUTIONS   OF  NITRO-CELLULOSE  59 

If  such  a  tendency  as  illustrated  above  exists,  it 
will  become  a  reality  through  the  disintegration  of 
equivalents  which,  in  combination,  correspond  to  a 
molecule  of  water,  H9O.*  The  removal  of  one-half  of 
the  alkali  from  cellulose  in  the  mercerization  process 
is  effected  by  the  action  of  the  alcohol  upon  the 
basic  groups  therein  ;  the  molecule  of  cellulose  should, 
therefore,  be  represented  so  as  to  permit  a  resolution 
of  the  original  material  into  acid  and  basic  sub-com- 
ponents through  the  disintegration  of  the  water- 
groups,  Under  this  assumption,  we  may  write  cellu^ 
lose  as 

H  H 

I  I 

H—  C—  O—  H    H—  O—  C—  H 


H-      I 
C—  O—  H   H—  0—  C 

II  I 

C—  O—  H    H—  O—  C 


I        -o^       I 

H—  C—  O--H    H—  O—  C—  H 


H  H 


*  It  will  be  observed  that  the  constituents  of  water,  H-O-H, 
form  the  central  linking  group  in  each  of  the  expressions 

H  H 

H  H  || 

H—  C—  O  —  C—  H 


and  |  | 

XHJT  H—  C—  HH—  C—  H 


H  H 


|| 
H  H 


60  SMOKELESS  POWDER 

which  would  resolve  into 

H  H 

H—  C—  O—  H    H—  O—  C—  H 

I  /H  | 

c<  o=c 

IXH  | 

C—  O—  H  H—  O—  C 
Form  I.            |i  || 

C—  O—  H  H—  O—  C 


c=o  c 

I  H/l 

H—  C—  O—  H    H—  O—  C—  H 


or 


H  H 

I  I 

H— C— O— H    H— O— C— H 

I  /H  | 

c<  o=c 

|\H  | 

C— O— H    H— O— C 
Form  II.  ||  II 

C— O— H    H— O— C 
| 

o=c 

| 
H— C— O— H    H— O— C— H 

I  I 

H  H 

The  molecule  as  above  written  contains  double  cen- 
tral carbon  bonds,  which  fact  permits  it,  on  its  enter- 
ing into  combination,  to  be  written  as 


SOLUTIONS   OF  NITRO-CELLULOSE 

H  H 

H—  C—  O—  H   H—  O—  C—  H 


6l 


|        -H        H  | 

—  C—  O—  H    H—  O—  C— 

_C—  O—  H    H—  O—  C— 


I       ^-D--        I 

H—  C—  O—  H    H—  O—  C— 

i  ' 


H 

Without  radical  modification,  it  may  be  expressed 
H— C— O— H    H— O— C— H 


H 


H—  C—  O—  H    H—  O—  C—  H 
H—  C—  0-H    H—  O—  C— 


H 


^  ^ 

H—  C—  O—  H°H—  O—  C—  H 
I  I 


as  corresponding  to  C,,H,0O10. 


62  SMOKELESS  POWDER 

Halving  it,  we  will  obtain 


corresponding  to  C,H10O6.* 

This  latter  form,  which  is  the  simplest  expression 
for  cellulose,  represents,  not  the  molecule,  but  the  type 
unit  of  cellulose,  as  it  enters  into  combination, 
through  its  four  free  single  carbon  bonds,  either  with 
other  similar  units,  by  polymerization,  or  with  other 
substances  by  chemical  combination. 


*  Written  singly,  in  a  similar  form,  but  with  closed  bonds,  the 
single  molecule,  CaHioOe,  may  be  expressed  as 


H      H 


Compare  also  with  Cross  and  Bevan,  "  Cellulose,"  p.  38,  where, 
in  reference  to  cellulose  acetates,  it  is  stated  if  the  above  formula 
(alluding  to  a  formula  cited)  be  established  by  further  and  ex- 
haustive investigation,  the  cellulose  unit  must  be  C6H6O.(OH)4. 


SOLUTION'S  OF  NITKO-CELLULOSE  63 

The  multiplicity  of  the  cellulose  derivatives  and  the 
generally  recognized  tendency  towards  polymerization 
already  alluded  to  suggest  the  further  amplification 
of  the  molecule  by  inter-combination  of  its  units 
through  connection  of  their  carbon  bonds  into  poly- 
meric forms,  the  type  of  which  may  be  expressed  as 
follows : 


Such  a  method  of  representation  possesses  a  special 
interest,  as  it  prepares  the  way  for  other  considerations. 
The  actual  number  of  phases  for  the  polymerized 
molecule  thus  expressed  may  vary  from  2  to  any 
desired  number.  In  the  above  diagram  a  5-phase 
form  is  presented  for  purposes  of  illustration.  The 
simple  molecule  with  its  four  free  carbon  bonds  as 


64 


SMOKELESS  POWDER 


presented  in  each  of  the  five  sectors  combines  with 
the  simple  molecule  in  each  adjacent  sector  on  either 
hand.  The  simplest  polymerized  form  that,  under  our 
theory,  can  stand  alone,  is  C]2HaoO10,  composed  of 
two  "sectors,"  the  carbon  bonds  in  each  of  which 
unite  with  those  of  the  other. 
Thus  we  have 


correcting  the  form  previously  written, 


H-C-O-H 

H 

The  5-phase  molecule,  or  its  polymer,  corresponds 
to  pyrocellulose. 

It  is  evident  that  under  such  an  assumption  the 
molecule  may  possess  an  infinity  of  phases.  There  is 
no  limit  to  their  number.  On  this  assumption,  and  it 


SOLUTIONS  OF  N1TRO-CELLULOSE  65 

seems  to  me  on  this  assumption  only,  may  we  account 
for  definite  chemical  composition  of  the  cellular  form 
in  the  plant  structure.  For  we  may  regard  the  cell 
as  built  up  from  an  aggregate  of  molecules  of  identical 
composition  but  of  progressively-varying  numerical 
phase.  The  cell  may  begin  with  molecules  of  low 
phase  and  end  with  molecules  of  high  phase,  or  con- 
versely. Molecules  of  progressively-varying  phase- 
magnitude  may  be  deposited  in  turn  from  protoplas^ 
mic  matter  in  particular  forms  of  different  density,  the 
successive  evolutions  providing  for  the  infinity  of  cel- 
lular structures  appreciable  to  the  human  eye,  which, 
in  their  successive  deposition,  build  up  the  fibrous  sub- 
stance of  the  cell. 

It  is  to  be  remembered  that  the  graphic  represen- 
tation of  molecular  arrangement  upon  a  plane  surface, 
— space  of  two  dimensions, — cannot  be  regarded  as 
more  than  a  conventional  device  illustrating  an  ar- 
rangement that  exists  in  nature  in  space  of  three 
dimensions.  Nevertheless,  the  conventional  ring- 
formed  combination  of  elemental  particles  shown  in 
the  polyphase  molecule  strongly  suggests  the  vortex- 
ring  theory  of  the  composition  of  matter  (as  applica- 
ble to  the  molecule].  For  whatever  the  atom  may  be, 
the  molecule  need  not  be  limited  in  composition  to 
the  simplest  collection  of  the  lowest  possible  mimber  of 
atoms  capable  of  entering  into  combination,  but  may 
be  built  up  from  a  very  great  number  of  the  elemental 
particles  taken  together  in  their  proper  ratios.*  Such 

*  On  this  hypothesis  the  atomic  weight  of  cellulose  would  be 
represented  by  an  average. 


66  SMOKELESS  POWDER 

a  molecule  would  increase  in  amplitude  according  to 
the  number  of  elemental  particles  entering  into  its 
composition ;  and  the  thought  therefore  suggests  it- 
self, that  progressive  variation  in  the  amplitude  of  the 
molecular  ring  is  a  characteristic  of  organic  life.  Or, 
conversely,  we  may  state  that  we  may  seek  for  the 
beginnings  of  organic  life, — at  least  of  plant-life, — in 
the  polymerization  of  the  carbohydrates. 

Briefly  summing  up,  the  conditions  governing  the 
formulation  of  cellulose  may  be  stated  as  follows : 

I. — The  capability  of  the  expression  of  the  molecu- 
lar formula  as  «(C6H10O6)  or  CeMH10ttO6M  justifies  the  as- 
sumption that  the  molecule  may  be  represented  as 
composed  of  n  number  of  similar  atomic  aggregations 
ol  the  form  CeH10O6,  these  aggregations  conjointly 
forming  the  molecule. 

2. — Under  the  assumption  that  Eder's  nitrates  repre- 
sent limits  of  nitration  in  the  sense  defined  by  Vieille, 
n  cannot  possess  a  value  less  than  2  ;  that  is,  CiaHaoOlt 
represents  the  lowest  expression  for  the  molecule. 

The  fact  that  2  :  i  ether-alcohol  dissolves  certain 
forms  of  nitro-cellulose  at  ordinary  atmospheric  tem- 
peratures with  greater  ease  than  any  other  compound 
solvent  containing  ether-alcohol  in  other  than  the  2  :  I 
proportion,  tends  to  show  that  all  the  OH  groups  in 
which  nitro-substitution  takes  place  are  not  similarly 
placed  within  the  molecule. 

4. — The  fact  that,  at  very  low  temperatures,  either 
ether  or  alcohol  singly  will  dissolve  soluble  nitro-cellu- 
lose, whereas  at  ordinary  atmospheric  temperatures 
a  mixture  of  the  two  solvents  is  required  to  effect 


SOLUTIONS   OF  NITRO-CELLULOSE  f 

solution,  implies  that,  under  influence  of  cold  (absence 
of  heat),  both  ether  and  alcohol,  on  the  one  hand, 
nitro-cellulose  on  the  other,  may  undergo  a  certain 
atomic  rearrangement  within  the  molecule. 

5. — If  symmetry  of  arrangement  exists  in  the  sub- 
components of  the  molecular  section — C6H10O, — per- 
mitting the  representation  of  atomic  aggregations 
which,  according  to  the  influences  to  which  they  are 
exposed,  may  exhibit  acid  actions  on  the  one  hand, 
basic  reactions  on  the  other,  it  would  be  by  groupings 
of  the  carbon  and  hydrogen  atoms,  which  are  even 
in  number,  around  the  oxygen  atoms,  which  are  odd 
in  number. 

6. — There  is  good  reason  for  the  assumption  (basis  of 
theory  of  nitro-substitution)  that  the  molecules  of  both 
cellulose  and  nitro-cellulose  are  of  similar  structure; 
that  there  is  no  general  rearrangement  of  the  atoms  of 
the  cellulose  in  the  process  of  nitration,  but  that  nitra- 
tion is  accomplished  through  the  substitution  of  nitryl 
for  replacable  hydrogen  in  certain  hydroxyl  groups,  the 
said  groups  retaining,  after  nitration,  the  position  in 
the  molecule  that  they  held  before  nitration,  as  already 
stated.  It  is  upon  this  assumption  that  we  represent 
the  molecule  of  cellulose  as  typical,  both  of  cellulose 
and  nitro-cellulose,  and  do  not  represent  the  substitu- 
tion of  the  nitryl  in  the  molcule,  unless  actually  refer- 
ring to  some  specific  property  of  the  nitro-cellulose 
distinguishing  it  from  the  original  cellulose. 

7. — Under  the  assumption  (i)of  the  basic  and  acid, 
positive  and  negative,  distribution  of  the  atoms  within 
the  molecule,  based  upon  the  conception  of  the  con- 


68  SMOKELESS  POWDER 

stitution  of  the  molecule  as  a  double  salt,  and  (2)  of 
the  action  of  the  compound  ether-alcohol  solvent  upon 
nitro-cellulose  at  ordinary  atmospheric  temperatures, 
and  of  the  action  of  both  the  ether  and  alcohol  sep- 
arately upon  nitro-cellulose  at  low  temperatures, 
we  may  regard  (a)  the  ethyl  ether,  (&)  the  ethyl 
alcohol  (which  possesses  the  composition  but  not  the 
atomic  arrangement  of  an  ether  [methyl]),  and  (c) 
the  nitro-cellulose,  which  possesses  the  characteristic 
properties  of  an  ether,  as  all  splitting  up  into  dual 
sub-groups.  The  manner  in  which  ethyl  ether  and 
ethyl  alcohol  could  so  split  up  symmetrically  is  easily 
shown  ;  regarding  nitro-cellulose  as  an  ether,  we  may 
seek  to  split  it  into  sub-groups  within  the  molecule 
in  a  similar  manner. 

The  three  type  forms  may  then  be  presented  as  fol- 

lows : 

Ethyl  alcohol  Ethyl  ether 

C.H.O  (C.HJ.O 

(Under  strain  as  methyl  ether) 

H  H 

H  H  || 

|    /H  Hv    |  H—  C—  O  —  C—  H 

/        \  i 


H—  C—  HH—  C—  H 
H  H  || 

H  H 

Nitro-cellulose 
(As  expressed  by  its  type,  cellulose) 

I  I 

H—  C—  O—  H     H—  O—  C—  H 


H—  C—  O—  H     H—  O—  C—  H 


SOLUTIONS   OF  NITRO-CELLULOSE 


That  all  nitro-celluloses  are  soluble  in  the  compound 
ether-alcohol  solvent,  notwithstanding  the  wide  differ- 
ences in  temperatures  at  which  solution  is  effected, 
leads  me  to  the  conclusion  that  all  nitro-cellulose 
molecules  are  of  similar  constitution  and  organization. 
That  they  are  of  a  dual  composition  is  evinced  by 
their  more  ready  solubility  in  the  compound  solvent ; 
again  the  fact  that  they  are  all  soluble  in  the  single 
solvent  ethyl  ether  leads  me  to  the  conclusion  that 
the  two  halves  of  the  dual  molecule  are,  with  respect 
to  each  other,  similar,  or  of  similar  inverted  forms. 
Therefore,  on  page  60,  Form  I  is  the  correct  diagram 
of  the  separation  of  the  factors,  rather  than  Form  II. 

We  have  considered  briefly  in  the  preceding  the 
composition  of  the  molecule  in  relation  to  mercer- 
ization,  polymerization,  nitration,  and  colloidization. 
It  remains  to  dwell  somewhat  more  fully  upon  the  re- 
actions of  nitration  and  hydration,  and  to  show  how 
they  are  reflected  in  the  modified  structure  of  the 
molecule. 

The  type  cellulose  has  been  written : 


By  changing  the  relative  position  of  atoms  of  hydro- 


SMOKELESS  POWDER 


gen,    and    without    altering    the    constitution    of    the 
molecule,  it  may  be  written : 


H-C—  O— H    H— 0-^3— H 


H-C-0— H    H 
H-C— 0— H    H— O 


H-C— 0-H    H— O- 


The  polymerized  molecule  is  composed  of  sections  of 
the  type : 


H_C_0-H    H-O-^-H, 
H_i_0-H    H-O-C— H 


From  an  examination  of  the  unit  of  polymerization  it 


H—  G—  O—  H     H—  O—  C—  H 


will  be  seen  that  the  atoms  of  carbon  are  connected  (i), 
by  single  bonds  with  each  other;  (2),  with  hydrogen 
bonds;  (3),  with  hydroxyl  bonds;  and  (4),  with  what 

may  be  termed  "  water  bonds,"  of  the  form  \         . 

XH 

Each  carbon  atom  is  connected  with  two  other  car- 
bon atoms,  one  on  either  side.  Every  third  carbon 


SOLUTIONS   OF  N ITRO-CELLULOSE  71 

atom  is  connected  with  the  di-valent  "  water  "  radicle 
(A).  The  remaining  two  of  each  set  of  three  carbon 
atoms  are  each  connected  with  one  atom  of  hydrogen 
and  one  hydroxyl  radicle  (B).  The  symmetrical  order 
of  arrangement  of  the  carbons  is  — BAB — BAB — 
BAB—. 

The  free  carbon  bonds  of  each  unit  represent  poly- 
merization. 

The  hydroxyl  radicles  represent  nitration,  in  the 
mean  and  higher  stages. 

The  "  water"  radicles  represent  mercer  ization,  and 
nitration  in  the  lower  stage. 

The  open  oxygen  bond  in  the  "  water  "  radicle  rep- 
resents colloidization  by  combination  of  the  half  mole- 
cule of  the  nitro-cellulose  with  the  half  molecule  of 
the  solvent. 

Nitration. — The  process  of  nitration  may  here  be 
taken  up  for  more  extended  consideration.  The  fibrous 
cellulose  reflects  in  its  chemical  behavior  a  character- 
istic of  plant  life,  namely,  the  possibility  of  altering 
growth  conditions  through  changes  of  temperature. 
The  reactions  into  which  it  enters  may  be  varied 
through  the  variation  of  the  temperature  at  which  the 
said  reaction  takes  place.  These  changes  in  rate  and 
character  of  reaction  as  due  to  temperature  are  espe- 
cially characteristic  of  nitration,  mercerization  and 
colloidization ;  and  doubtless,  during  the  original 
growth  processes  of  the  plant,  affect  polymerization. 
The  effect  of  temperature  upon  nitration  is  reflected  in 
the  resultant  nitrated  product  in  two  ways:  (i)  in 
raising  the  degree  of  nitration  in  proportion  to  the 


72  SMOKELESS  POWDER 

increase  in  temperature  (within  certain  limits) ;  and  (2) 
in  increasing  and  modifying  solubilities  corresponding 
to  given  nitrations. 

Until  very  recently,  our  actual  knowledge  of  the 
nitration  of  cellulose  may  be  said  to  have  been  con- 
fined to  the  following  facts : 

I. — That  there  was  a  lower  limit  of  obtainable  nitra- 
tion, somewhere  between  that  represented  by  the 
compounds  C13H14O4(OH)6(NO9),  for  which  N  =  3.80, 
and  CiaH14O4(OH)4  (NO,),,  for  which  N  =  6.76. 

2. — That  there  exists  an  upper  limit  of  attainable 
nitration,  somewhere  near  that  of  the  hexanitrate  of 
Eder,  CiaH14O4(NO8)6,  for  which  N  =  14.14. 

3. — That  nitration  is  progressive  between  these 
limits ;  and  that  when  determined  at  a  given  tempera- 
ture, it  advances  gradually  and  progressively  from  the 
lower  towards  the  higher  limit,  while  under  certain 
conditions  it  may  be  made,  similarly,  to  decrease. 

4. — That  somewhere  between  the  attainable  limits  of 
nitration  a  point  is  reached  (and  the  point  is  not  con- 
stant so  far  as  relates  to  degree  of  nitration)  where  the 
nitrated  product  ceases  to  be  soluble  at  a  given  mean 
atmospheric  temperature  in  a  mixture  of  ethyl  ether 
and  ethyl  alcohol.  This  fact  was  utilized  to  separate 
the  so-called  '*  soluble"  nitrates  of  celluloses  of  low 
nitration  from  the  ' '  insoluble  ' '  nitrates  of  high  nitra- 
tion. 

Let  us  consider  the  formula  for  the  double-type 
molecule  in  connection  with  the  six  nitrates  for- 
mulated by  Eder,  and  let  us  assume  that  there  has 
been  isolated  from  the  substance  of  the  cellulose  for 


SOLUTIONS   OF  NITRO-CELLULOSE  73 

purposes   of    experimentation    a   homogeneous   body 


Negative 
Acid 


H-C— O-H   H-O-C— H 

H-C— O-H   H-O-C— H. 
H-C— O-H   H-O-C— H 

H-C-O-H   H-O-C— H 


Positive 
Basic 


composed  of  molecules  of  the  above  2-phase  form. 
Then,  if  there  are  six  nitrates,  we  could  form  them 
successively  by  substituting  nitryl  for  the  replaceable 
hydrogen  in  the  "  water"  and  "hydroxyl"  radicles  of 
the  cellulose  on  one  side  of  the  molecule.  Substituting 
thus  in  the  above  diagram  we  would  have,  for  the 
highest  nitrate 


Negative 
Acid 


H-C—  O—  NO2    H-O-C—  H 


TT-6—  O—  NO2    H-O-<JMEt 
•H-C-O—  NO2    H-O-C—  H 

6-=^o^0J3>6 

H-6—  O—  ;NO2    H-O—  t—  H 


Positive 
Basic 


On  account  of  the  ready  solubility  of  the  lower 
nitrates  in  ethyl  alcohol  at  ordinary  temperatures  the 
maximum  efficiency  of  the  2  :  I  ether-alcohol,  and  the 
solubility  of  the  highest  nitrates  in  ethyl  ether,  we 
assume  that  the  replaceable  hydrogen  atoms  in  the 
water  radicles  are  replaced  by  nitryl  first,  and  that 
subsequently  the  nitro-substitution  continues  through 
the  displacement  of  the  hydrogen  in  the  hydroxyl 
radicles.  If  we  regard  alcohol  as  connected  with  the 


74 


SMOKELESS  POWDER 


positive  (basic)  side  of  the  molecule,  and  ether  with 
the  negative  (acid)  side,  we  may  represent  nitration, 
for  the  higher  nitrates  (say, the  hexanitrate),  as  follows: 


Negative 
Acid 


H-C— O— NO2    H-O-C— H 

<H S~°-NQH> 

H-C— O— N02  •  H-O-C— H 
H-C-O— NO2  H-O-C— H 
-H  I  NOi^i 


O— N02    H-O-C-H 


Positive 
Basic 


Under  such  conditions,  we  may  formulate  the 
nitrates  of  cellulose  for  the  2-phase  molecule  as  fol- 
lows: 

TABLE  V 

Cellulose  hexanitrate,  CiaH14(NO,)6O10. 

Cellulose  pentanitrate,  C12O16(NO,)6O10. 

Cellulose  tetranitrate,  CiaO16(NO,)4O10. 

Cellulose  trinitrate,  C31H17(NO3)SO10. 

Cellulose  dinitrate,  C17H18(NO,),O10. 

Cellulose  mononitrate,  C12H19(NO2)O10. 

If  we  turn  from  the  consideration  of  the  theoretical 
2-phase  cellulose  above  represented  to  that  of  actual 
cellulose,  we  will  find  that  the  latter  may  be  resolved 
into  cellulose  nitrates,  not  in  six,  but  in  a  very  great 
number  of  ways.  Every  molecule  may  be  differently 
affected  in  the  process  of  nitro-substitution.  The 
character  and  composition  of  the  resultant  product  may 
vary  with  strength  of  acid,  its  relative  quantity  in  pro- 
portion to  the  cotton  taken  (this  determines  the  rate 
of  absorption  of  water  formed  during  the  reaction), 


SOLUTIONS   OF  NITRO-CELLULOSE  J$ 

the  temperature  at  which  the  reaction  takes  place,  and 
the  duration  of  immersion  in  the  acid  bath.  The 
cotton  may  be  nitrated  on  the  surface  of  the  fibre  or 
nitrated  wholly  throughout ;  it  may  represent  a  mix- 
ture of  soluble  and  insoluble  nitrates  or  it  may  possess 
a  uniform  degree  of  nitration ;  and  it  may  exhibit 
variations  (for  the  same  chemical  composition)  in  its 
solubilities  in  standard  solvents;  for  the  successive 
polyphase  molecules  are  differently  constituted  and 
differently  placed,  and  doubtless  afford  progressively- 
varying  resistances  to  the  effect  of  the  acid  bath. 

It  will  be  remembered  that  the  theoretical  limiting 
of  nitration  (14. 14  per  cent,  nitrogen)  was  not  obtained 
by  Eder.  Probably  the  ultimate  substitution  of  nitryl 
for  every  atom  of  replaceable  hydrogen  is  a  limit  that 
may  not  be  attained  in  practice.  Doubtless  some  of 
the  molecules  do  represent  complete  replacement, 
while  others  are  considerably  removed  from  complete 
transformation.  It  will  be  shown  hereafter  that  by 
colloidization  the  molecular  amplitude  of  the  nitro- 
cellulose is  reduced  to  a  mean,  but  such  is  not  the 
case  for  the  fibrous  material. 

Hydration. — When,  in  the  attempt  to  nitrate  cellu- 
lose, the  strength  of  the  acid  mixture  is  reduced  below 
a  certain  figure,  a  remarkable  phenomenon  may  be  ob- 
served— instead  of  a  nitration  there  may  be  produced  a 
hydration.  We  may,  therefore,  assume  that  from  the 
same  point  of  weakness  in  the  molecule  there  may  de- 
velop either  a  nitro-substitution  (nitration),  or  else  an 
atomic  rearrangement  accompanied  by  an  absorption  of 
water  (hydration).  It  has  already  been  stated  that  ni- 


?  SMOKELESS   POWDER 

tration  starts,  in  accordance  with  our  theory,  in  nitro-sub- 
stitution  in  the  water  radicles,  producing  nitro-celluloses 
soluble  in  the  alcohol  (basic)  solution.  The  hydration, 
then,  should  start  in  the  rearrangement  of  the  parts  of 
the  molecule  adjacent  to  these  water  radicles.  The 
quantity  of  water  that  is  to  be  absorbed  or,  rather, 
taken  up  into  the  substance  of  the  molecule,  may,  as 
shown  by  Cross  and  Bevan  in  their  references  to  mer- 
cerization,  approach  the  limit  CiaHaoOJ0.2HaO  ;  corre- 
sponding to  CiaHaoO10.2NaOH  ;  while  the  definite  hy- 
drate, CiaHaoO,0.  HaO,  containing  half  as  much  water, 
and  corresponding  to  CiaH20O10.NaOH,  is  readily  iso- 
lated. We  have,  therefore,  as  definite  limits,  the  in- 
corporation into  the  molecule  of  cellulose,  C13HaoO10  , 
of  water  in  the  two  ratios,  2H,O  and  HaO. 

I  /  °  \  I 
Now  the  radicle  C<  >C    plus    H,O    becomes 

|    \HH/    | 
H—  C—  O  —  H     H—  O—  C  —  H  ;  and  as  the  water  radicle 

i  i 

occurs  twice  in  the  double  molecule  C,,H,0O,0  ,we  have 
for  the  full  transformation, 

i  i 

H—  C—  O—  H     H—  O—  C—  H 


H—  C—  O—  H     H—  O—  C—  H 

I  |  +  H,0  = 

H—  C—  O—  H     H—  O—  C—  H 


H—  C—  O—  H     H—  O—  C—  H 


SOLUTIONS   Of  NITRO-CELLULOSE  77 


and 


H—  C—  O—  H  H—  O—  C—  H 

I  I 

H—  C—  O—  H  H—  O—  C—  H 

—  C—  O—  H 


H 


H—  C—  O—  H     H—  O—  C—  H 


H—  C—  O—  H     H—  O—  C—  H 


O— H     H— O— C— H 


H—  C—  O—  H     H—  O—  C—  H 

I  I  +  *H90  = 

H—  C—  O—  H     H—  O—  C—  H 


H—  C—  O—  H     H—  O—  C—  H 


— O— H  H—O— C— H 

H— C— O— H  H— O— C— H 

H— C— O— H  H— O— C— H 
I  I 

H— C— O— H  H— O— C— H 
I  I 

H— C— O— H  H— O— C— H 
I  | 

H— C— O— H  H— O— C— H 


?  SMOKELESS   POWDER 

In  considering  these  forms  of  modification  of  the 
molecular  structure  it  should  be  remembered  that  the 
molecules  of  the  original  fibre  are  characterized  by 
their  variations  in  amplitude.  And  we  know,  actually, 
that  hydration  represents  a  breaking  down  of  the  cell- 
fibre.  This  breaking  down  is  also  illustrated  in  the 
two  diagrams  of  the  modified  molecules  just  presented. 
In  the  former  it  will  be  observed  that  but  one  of  the 
two  water-bonds  remains;  in  the  latter,  that  both 
water  radicles  have  disappeared  and  that  the  two 
halves  of  the  molecule  appear  wholly  separated. 

The  effect  of  hydration  in  breaking  down  the  fibrous 
structure  of  the  cotton  and  ultimately  putting  it  into 
solution  may  therefore  be  explained  by  the  following 
steps : 

I . — The  fibre  exists  as  an  aggregation  of  cells  of  vary- 
ing amplitude.  The  solvent  .at  first  attacks  those  cells 
that  are  either  the  weakest  or  most  exposed,  and  trans- 

I  /  °  \  I 
forms  in  them  some  of  the  water  radicles,   C^  ^  C, 

\\HH/ \ 

\  I 

into  the  hydroxyl  forms,  H— C— O— H    H— O— C— H. 

I  I 

The  result  is  a  partial  transformation  into  C,aHaoO1(l'- 

H30  =  (CiaHaaOu). 

2. — As  hydration  proceeds,  the  attack  takes  place 
throughout  all  molecules  irrespective  of  amplitude  un- 
til in  each  molecule  one-half  of  the  water  radicles  are 
transformed  into  hydroxyl  forms,  and  a  material,  yet 
fibrous,  built  up  of  modified  cells  of  varying  ampli- 
tude in  each  of  which  one-half  of  the  water  radicles 


SOLUTIONS   OF  NITRO-CELLULOSE  79 

are  transformed  into  hydroxyl  forms,  results.  This  is 
the  true  hydrocellulose,  CiaHaoO10.H,O,  or,  more  prop- 
erly, CiaHaaOn. 

3. — As  hydration  proceeds,  transformation  advances 
towards  the  total  conversion  of  all  the  water  radicles 
into  hydroxyl  radicles.  This  is  accompanied  by  dis- 
integration of  the  fibre  and  a  tendency  to  enter  into 
solution.  The  formula  shows  that  with  total  trans- 
formation of  the  water  radicles  into  hydroxyl  forms 
the  molecule  splits  up  into  two  halves,  between  which 
there  is  no  chemical  union ;  therefore  actual  chemical 
combination  of  the  two  halves  ceases,  and  there  can  be 
no  chemical  connection  between  them  except  such  as 
may  be  represented  by  electrolytic  strain. 

4. — As  solution  becomes  actually  effected,  the  fourth 
and  last,  and  perhaps  the  greatest,  change  in  the  series 
occurs.  By  their  intimate  contact  and  admixture  the 
dissolved  molecules,  freed  from  their  organic  form  of 
aggregation,  are  reduced  to  a  common  amplitude. 
They  hereafter  constitute  amorphous  cellulose,  and 
may  be  represented  as  an  aggregate  of  the  form 
«C6H10O6.  It  is  probable,  however,  that  the  number 
of  atomic  particles  in  each  molecule  still  remains  ex- 
ceedingly great,  as  progressive  nitration  still  appears 
to  occur  for  this  material. 

5. — The  transformation  of  the  whole  substance  of  the 
cellulose  into  the  form  corresponding  to  CiaHaoO10.2HaO 
represents  the  dividing  line  between  the  chemical  and 
the  physical  aspects  of  the  absorption  of  water  into 
the  substance  of  the  molecule.  Any  greater  absorption 
of  water  than  that  corresponding  to  C,,HMOU.2H,O 


80  SMOKELESS  POWDER 

pertains  to  simple  solution;  any  less  absorption,  to 
chemical  change,  affecting  the  structure  of  the  cellulose 
cell. 

6. — The  hydrocellulose  obtained  by  the  usual  pro- 
cesses represents,  simultaneously,  a  combination  of 
all  the  above-described  processes.  Part  of  the  cellu- 
lose remains  wholly  unattacked,  and,  if  allowed  to 
exist,  renders  the  whole  mass  what  the  workmen  style 
"woolly";  part  is  converted  into  ClaHaJOn,  a  true 
hydrocellulose,  which,  inasmuch  as  its  fibre  still  ex- 
ists, combines  to  exercise  the  same  effect  upon  the 
physical  constitution  of  the  mass  as  the  unnitrated 
portion ;  part  is  precipitated  as  wholly  hydrated  cellu- 
lose of  the  form  CiaH20O10.2HaO,  and  part  goes  into  so- 
lution. 

7. — Once  the  fibrous  structure  is  lost  by  solution, 
and  the  molecules  reduced  to  a  common  amplitude, 
the  organic  constitution  is  gone  and  may  not  be  re- 
covered in  any  way.  The  cellulose  thereafter  remains 
as  an  amorphous  body.  This  condition  finds  a  parallel 
in  the  ultimate  state  of  colloided  nitro-cellulose,  when 
the  last  traces  of  solvent  are  totally  expelled  there- 
from, and  there  results  a  pulverulent  amorphous  mass. 


APPENDIX    I 

RESEARCHES  UPON  THE  NITRATION  OF  COTTON 
By  M.   VIEILLE 

VERY  different  formulae  have  been  suggested  to 
represent  the  composition  of  the  nitro-products  de- 
rived from  celluloses,  and  particularly  the  composi- 
tion of  products  of  maximum  and  minimum  nitration. 
These  products  were,  moreover,  obtained  by  processes 
differing  at  the  same  time  both  as  to  temperature  of 
reaction,  concentration  of  acids,  and  the  nature  of  the 
sulpho-nitric  mixtures  employed.  Therefore  the  re- 
sults were  not  susceptible  of  any  general  interpreta- 
tion. 

We  have  thought  it  well  to  take  up  this  study 
again  in  a  methodical  manner,  and  to  investigate  the 
influence  of  different  methods  of  nitration  and  of 
temperature  upon  resultant  products. 

I.    FIRST   METHOD    OF   NITRATION* 

Conditions  of  dipping. — We  first  decided  to  deter- 
mine the  law  in  accordance  with  which  the  degree  of 

*In  translating  this  paper  I  have  converted  the  chemical  for- 
mulae employed  therein  into  those  of  the  system  employed  in  the 
United  States  (O  =  16). 

ll 


82  SMOKELESS  POWDER 

nitration  and  physical  qualities  vary  under  well-de- 
fined conditions  of  dipping,  namely,  dipping  in  pure 
nitric  acid  of  various  degrees  of  concentration  and  at 
a  temperature  of  11°  C. 

The  nitration  was  effected  by  immersing  wadded 
cotton  in  from  100  to  150  times  its  weight  of  acid; 
all  elevation  of  temperature  was  thus  obviated  and 
the  strength  of  acidity  of  the  bath  could  be  regarded 
as  constant  during  the  whole  of  the  dipping. 

The  operations  were  conducted  in  large-mouthed, 
stoppered  flasks  of  about  500  c.c.  capacity  and  cooled 
externally  by  a  current  of  water.  The  flasks  con- 
tained about  250  c.c.  of  nitric  acid.  Three  grams  of 
well-carded  cotton  were  introduced  into  the  upper  part 
of  the  vessel  which  was  then  corked  and  shaken  four 
or  five  times,  whereby  the  cotton  was  equally  dis- 
tributed throughout  the  interior,  so  that  each  fibre 
might  be  considered  as  surrounded  by  150  times  its 
weight  of  acid. 

Percentage  of  nitration. — The  content  of  nitrogen 
in  the  nitrated  product  was  determined  by  M.  Schloes- 
sing's  method  for  estimating  nitrogen  in  nitrates.  In 
order  to  apply  this  method  to  the  determination  of 
nitrogen  in  explosives,  it  had  to  undergo  some  modi- 
fications in  detail,  which  show  at  the  same  time  the  de- 
gree of  exactness  realized  in  the  conditions  we  have 
adopted.  The  following  table  presents  a  resum£  of 
the  reults  of  our  experiments : 


THE  NITRATION  OF  COTTON 


E-O 

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Character  of  Specimei 

[trated  product  resembles  c 
sly  soluble  in  acetic  ether; 
in  pure  ether  or  ether-ak 

e  completely  in  acetic  etr 
hoi.  The  fibre  is  not  atta 

itrated  product  has  the  sa 
on.  It  becomes  gelatinou 
of  acetic  ether  and  ether- 

i  dissolves  in  the  acid;  pr 
id  precipitable  by  water, 
lined  swells  up  through  th 
:r  and  becomes  gelatinous 
Ether-alcohol  produces 

roduct  is  extremely  friabl( 
he  form  of  a  paste.  Nei 
ether-alcohol  produces  an 

ue  becomes  more  and  me 
ngly  blackened  by  the  acti 
.  Nitration,  insignificant 

c  ~~ 

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I1*! 

84  SMOKELESS  POWDER 

The  number  of  cubic  centimetres  indicated  in  the 
third  column  corresponds,  for  each  degree  of  concen- 
tration of  the  acid  taken,  to  the  maximum  nitration. 

Determination  of  the  maximum  nitration. — This 
maximum  was  determined  in  each  case  by  the  analy- 
sis of  specimens  exposed  to  times  of  dipping  of  in- 
creasing lengths.  The  limit  is,  moreover,  very  clearly 
indicated  by  employing  a  solution  of  iodine  in  iodide 
of  potassium,  which  produces  a  black  or  greenish  dis- 
coloration of  nitro-products  containing  traces  of  non- 
attacked  cotton.  We  may  state  that,  beyond  the 
point  where  the  discoloration  ceases  to  be  produced, 
prolongation  of  dipping  does  not  increase  the  degree 
of  nitration. 

Thus  a  specimen  dipped  in  acid  of  density  1.488 
gave  at  the  end  of  24  hours  of  dipping  161  c.c.,  and 
was  discolored  by  iodine.  At  the  end  of  70  hours  it 
gave  165.7  c-c'>  without  discoloration. 

On  the  other  hand,  a  specimen  dipped  in  acid  of 
density  1.490  ceased  to  be  discolored  by  iodine  after 
a  dipping  of  24  hours  and  gave  183.7  c-c-  At  the 
end  of  128  hours  the  same  specimen  gave  183.8  c.c. 

Nature  of  the  reactions ;  speed  of  reactions. — The 
durations  of  dipping  which  determine  maximum  nitra- 
tion vary  considerably  with  the  degree  of  concentra- 
tion of  the  acid.  The  rapid  action  for  the  density  of 
1.500  (at  the  most  from  two  to  three  hours)  becomes 
gradually  slower,  and  requires  for  the  density  of  1.483 
as  much  as  120  hours.  The  corresponding  nitro-prod- 
ucts practically  preserve  the  appearance  of  the  original 
cotton,  but  for  a  density  of  about  1.470  the  action  is 


THE   NITRATION    OF  COTTON  8$ 

completely  modified,  the  cotton  swells  and  dissolves 
almost  instantly,  transforming  the  acid  into  a  clear, 
transparent  collodion.  If  this  syrupy  mass  is  poured 
into  running  water  small  white  flocks  are  obtained, 
opaque  and  brittle  after  drying,  and  which  preserve 
nothing  of  the  primitive  fibre  of  the  cotton.  In  these 
conditions  the  limit  of  nitration  is  rapidly  reached. 
Acid  of  density  1.469  gives  after  5  minutes,  134.7  c-c- 1 
after  30  minutes,  140.5  c.c.  ;  after  20  hours,  139.3  c.c. 

When  the  density  of  the  acid  falls  below  1.46,  solu- 
tion does  not  occur;  the  action  becomes  much  slower 
and  the  cotton  appears  unattacked,  but  it  is  shown 
upon  washing  that  the  fibres  become  very  friable.  A 
specimen  was  collected  in  the  form  of  a  paste.  At 
the  same  time  the  yields  decrease  very  considerably 
below  the  theoretical  figure,  which  indicates  that  the 
cotton  has  been  partially  attacked. 

For  densities  below  1.450  it  is  no  longer  possible  to 
isolate,  however  long  the  dipping,  a  product  that  is 
not  blackened  by  iodine.  The  cotton  is  slowly  trans- 
formed into  products  non-precipitable  by  water;  e.g., 
at  the  end  of  15  days  there  is  obtained  by  treatment 
in  water  a  very  small  residue  which  is  intensely  colored 
black  or  blue  by  iodine,  and  which  is  of  a  very  feeble 
nitration. 

Discontinuities  in  the  progress  of  nitration. — The  pre- 
ceding table  shows  that,  under  the  above-mentioned 
conditions  of  dipping,  the  degree  of  nitration  of  the 
cotton  increases  more  or  less  gradually,  in  accordance 
with  the  concentration  of  the  nitric  acid,  from  108  c.c. 
to  about  128  c.c. ;  the  degree  of  nitration  then  rises 


86 


SMOKELESS  POWDER 


to  140  c.c.,  corresponding  to  a  very  small  variation 
in  the  strength  of  the  acid,  and  it  remains  at  this  fig- 
ure while  the  concentration  of  the  acid  increases  to  a 
very  notable  extent.  It  again  rises  under  similar 
conditions  to  165  c.c.,  then  to  about  180  c.c.,  and 
then  increases  gradually  to  the  limits  of  nitration  of 
gun-cotton  properly  so-called. 


180 
J65 


140 
130 


1.460 


1.470 


1.480 


1.490 


The  above  diagram,  obtained  by  expressing  the 
density  of  the  acid  by  abscissae  and  the  corresponding 
percentage  of  nitration  by  ordinates,  illustrates  the 
character  of  the  progress  of  the  reaction. 

The  existence  of  these  discontinuities  is  of  great 
importance  in  relation  to  the  establishment  of  the 
chemical  formulae  of  the  nitro-derivatives  of  celluloses. 
It  has  therefore  been  deemed  useful  to  reproduce 


THE   NITRATION   OF  COTTON  »/ 

these  different  degrees  of  nitration  under  entirely  dif- 
erent  conditions,  employing  sulpho-nitric  mixtures. 


II.    SECOND    METHOD    OF   NITRATION 

We  employed  sulpho-nitric  mixtures  formed  of 
ordinary  sulphuric  acid  (density  1.832)  and  ordinary 
nitric  acid  (density  1.316).  The  conditions  of  dipping 
were  identical  with  those  which  have  already  been 
described;  3  grams  of  wadded  cotton  in  250  c.c.  of 
the  mixture.  The  temperature  varied  from  19°  C. 
to  21°  C. 

The  following  table  presents  a  resum£  of  our  exper- 
iments. The  first  column  shows  the  proportion  by 
volume  of  nitric  acid  to  sulphuric  acid  taken : 


Preparation  of 
H.SO4  by  volume 
for  i  vol.  of  HN03 
A  =  1.316 

No.  of  c.c.  of  NO, 
evolved  from  i  gm. 
of  the  Nitrated 
Product  at  o°  C. 
and  760  m.m.  , 

Character  of  Specimens 

3-00 
2.50 

2.00 
1.70 
1.50 

195-9 
190.1 
184.6  ) 
185.5^ 
182.3) 

Cotton  not  attacked.  Soluble  in 
acetic  ether  and  in  ether-al- 
cohol 

I.4O 
1.30 
1.20 

164.0) 
i66.7V 
166.0  ) 

The  cotton  is  very  slightly  at- 
tacked (a  little  stringy).  Sol- 
uble in  acetic  ether  and  gen- 
erally becomes  gelatinous  by 
the  action  of  ether-alcohol 

1.  10 
I.OO 

141.2  ) 
143-5  f 

Rendered  gelatinous  by  acetic 
ether.  Is  only  swelled  up  by 
ether-alcohol 

0-95 
O.gO 

133.3  (. 
132.7) 

Friable  products 

88 


SMOKELESS   POWDER 


These  results  give  rise  to  various  observations. 

The  sharp  advances  in  the  degree  of  nitration  indi- 
cated in  the  first  method  are  equally  to  be  observed 
under  the  second,  and  practically  for  the  same  con- 
tents of  nitrogen,  corresponding  to  a  yield  of  130  c.c., 
140  c.c.,  165  c.c.,  and  180  c.c.  of  nitrogen  dioxide, 
approximately. 

Thus  the  degree  of  nitration  remains  the  same  for 
proportions  of  sulphuric  acid  of  2,  1.70,  and  1.50;  and 
lowers  abruptly  by  1 8  c.c.  for  the  proportion  of  1.40. 
Nitration  remains  stationary  for  the  proportions  of 
1.40,  1.30,  and  1. 20,  and  lowers  again  abruptly  for 
the  proportions  i.io  and  i.oo. 

In  order  to  follow  this  phenomenon  more  closely  we 
undertook  dippings  with  proportions  of  acid  interme- 
diary between  those  for  which  the  abrupt  changes  had 
been  observed. 

The  specimens  thus  obtained  gave  the  following 
results : 


Preparation  of 
H-SO4  by  volume 
for  i  vol.  of  HN03. 
A  =  1.316. 

No.  of  c.c.  of  NO, 
evolved  from  i  gm. 
of  Nitrated  Product 
at  o°  C.  and  760 
m.m. 

Character  of  Specimens 

1-45 

I7I.I 

Cotton  not  attacked.     Soluble  in 
ether-alcohol 

1.  15 

153-0 

Cotton  attacked  slightly 

The  percentage  of  nitration  is  interpolated  exactly 
between  those  indicated  above.  These  trials  confirm 
the  preceding  experiments,  which  show  that  the  exact- 
ness of  the  mixtures  under  the  conditions  of  our  ex- 


THE  NITRATION  OF  COTTON 


89 


periments  may  be  relied  upon  and  that  the  discontin- 
uities indicated  do  not  arise  from  accidental  conditions. 
They  show,  moreover,  that  there  are  not,  properly 
speaking,  sharp  advances  in  nitration ;  and  that  there 
exists  a  very  restricted  zone  of  acid  mixtures  with 
which  one  may  obtain  intermediate  nitration.  But 
there  exists,  nevertheless,  a  discontinuity  in  the  prog- 
ress of  the  reaction ;  and  the  following  diagram, 
obtained  by  expressing  the  percentages  of  sulphuric 
acid  in  a  mixture,  as  abscissae,  and  the  yield  of  nitro- 
gen in  c.c.,  as  ordinates,  allow  us  to  keep  track  of  the 
progress  of  the  reaction : 


.180 


165 


7   8   9   JO   11   12   13   14   15   16   17   18   19   20   21 

It  appears  rational  to  admit  that  definite  products 
correspond  to  the  periods  of  constant  nitration,  and 
that  the  mixture  of  the  two  products  only  occurs  in 
the  intervals  of  transition. 


90  SMOKELESS   POWDER 

The  properties  of  the  cellulose  nitrates  obtained  by 
the  second  process,  in  respect  to  solvents  such  as 
acetic  ether  and  ether-alcohol,  are,  for  a  given  degree 
of  nitration,  identical  with  those  of  the  nitro-cellulose 
obtained  by  dippings  in  pure  nitric  acid.  The  prop- 
erties of  cellulose  nitrates  appear  then  connected  with 
their  chemical  composition,  and  are  independent  of 
the  method  of  preparation. 

We  have  been  able  to  establish  this  fact  in  a  more 
rigorous  manner  by  nitro-celluloses  capable  of  conver- 
sion into  collodions. 

The  zone  of  collodions,  according  to  our  experi- 
ments, is  narrow.  It  comprises  celluloses  the  nitrogen 
content  of  which  is  comprised  between  180  c.c.  and 
190  c.c.,  approximately. 

A  little  above  this  limit  however,  up  to  195  c.c., 
and  a  little  below,  to  166  c.c.  and  often  to  150  c.c., 
celluloses  occur  which  are  transformed  into  jellies  by 
the  action  of  ether-alcohol,  and  which  filter  by  press- 
ure through  cloth.  But  it  has  been  found  that  these 
substances  do  not  produce  fluid  and  limpid  collodions 
useful  in  the  arts;  and  on  drying,  collodions  of  low 
nitration  have  been  found  to  yield  an  opaque  and 
brittle  film. 

Now,  all  the  nitro-celluloses  capable  of  producing 
collodions,  obtained  from  widely  different  sources,  and 
which  we  have  had  occasion  to  examine,  are  capable, 
in  accordance  with  their  composition,  of  being  arranged 
in  the  method  that  our  experience  has  made  clear  to 
us.  This  is  shown  in  the  following  table : 


THE   NITRATION   OF  COTTON  9 1 

Collodion-cotton,  Rousseau  process, 183.2  c.c. 

«              "        Billault-Billaudot 183.8  " 

High-temperature  cotton  Rousseau,  1st  lot  184.0  " 

"              "                 "              "          2d    "  189.0  " 
Swedish  gun-cotton  for  the  manufacture  of 

gelatin-dynamite r93-O  " 

Swedish  soluble  cotton  made  at  Vonges, 

in  accordance  with  the  directions  in  the 

aide-memoire  de  la  marine 185.4  " 

III.    HIGHER   LIMIT   OF   DEGREE   OF   NITRATION 

The  higher  limit  of  the  degree  of  nitration  does  not 
appear  in  the  preceding  tables,  which  do  not  present 
results  relating  to  a  density  of  nitric  acid  higher  than 
1.502.  Greater  densities  are  difficult  to  obtain  and, 
moreover,  our  first  trials  with  an  acid  of  1.516  strength 
at  a  temperature  of  15°  C.  resulted  in  a  very  marked 
attack  upon  the  cotton.  It  is  probable  that  dipping 
in  acids  of  so  great  a  concentration  would  only  give 
good  results  at  lower  temperatures,  but  the  upper  limit 
of  nitration  of  gun-cotton  may  be  obtained  indirectly 
by  the  use  of  sulpho-nitric  mixtures.  These  mixtures, 
which  were  employed  for  the  preparation  of  gun-cot- 
ton for  military  uses,  produce  products  yielding  from 
208  c.c.  to  212  c.c.  of  nitrogen  dioxide  per  gram. 

By  proceeding  with  special  care,  we  have  been  able 
at  a  temperature  of  11°  C.  to  exceed  these  limits  and 
to  obtain  a  product  of  215  c.c.  This  limit  remains 
exactly  the  same  whatever  the  proportions  of  nitric  or 
sulphuric  acid  employed,  even  when  Nordhausen  sul- 
phuric acid  is  substituted  for  the  monohydrate. 


92 


SMOKELESS  POWDER 


The  influence  of  a  great  excess  of  sulphuric  acid 
affects  exclusively  the  rapidity  of  the  process  of  nitra- 
tion, which  is  thereby  considerably  diminished. 


IV.   CELLULOSE  INCOMPLETELY  NITRATED 

The  preceding  results  related  to  celluloses  of  maxi- 
mum nitration,  and  the  iodine  reaction  above  indicated 
permits  us  to  regard  the  latter  as  homogeneous  bodies ; 
but  it  is  possible,  by  stopping  the  reaction  arbitrarily, 
to  obtain  an  idefinite  number  of  celluloses  of  the 
same  degree  of  nitration  and  of  variable  properties — 
mixtures  of  different  nitro-celluloses  and  unattacked 
cotton. 

Among  these  products  we  have  made  a  special  study 
of  those  which  were  furnished  by  the  sulpho-nitric 
mixtures.  On  increasing  the  proportion  of  sulphuric 
acid  in  the  mixture  we  may  so  slow  down  the  reaction 
as  to  obtain  for  a  given  duration  of  dipping,  say 
15  minutes,  any  degree  of  mean  nitration  desired. 
The  following  table  shows  the  composition  of  speci- 
mens submitted  during  variable  times  to  the  actions 
of  different  acid  mixtures  : 


Composition  of  the  Mixtuies 

Vol.  of  Nitrogen  Dioxide 
evolved   per  gram 

HNO3 

H3S04 

After  15  min. 

After  3  hours 

I  volume 
I  volume 
I  volume 
I  volume 

3  volumes 
3£  volumes 
4  volumes 
5  volumes 

194.6 
182.0 
150.8 
123.4 
126.8 

212.4 
212.4 
200.7 
2OO-7 
2OO.7 

THE  NITRATION  OF   COTTON  93 

All  specimens  which  have  been  exposed  to  only  fif- 
teen minutes  of  dipping  are  blackened  more  or  less 
strongly  by  iodine,  which  indicates  the  presence  of 
variable  quantities  of  non-attacked  cotton ;  the  second 
column  of  the  table  appears  to  show  that  the  excess  of 
sulphuric  acid  only  affects  the  speed  of  the  reaction, 
and  that  all  products  tend  toward  the  same  limit  of 
nitration. 

Moreover,  we  may  verify  the  fact  that  from  the  very 
beginning  of  the  reaction  the  products  obtained  are  of 
maximum  nitration,  and  that  the  results  of  rapid  dip- 
ping in  concentrated  acids  are  simply  mixtures  of  non- 
attacked  cotton  and  products  of  the  highest  nitration. 

Thus  the  sample  which  yields  126.8  c.c.  treated  in 
acetic  ether  loses  59.44  percent,  of  its  weight,  and  the 
residue  presents  all  the  characteristics  of  almost  pure 
cotton;  combustion,  and  coloration  by  iodine  (black 
coloration  very  feeble  in  the  presence  of  ferrous 
salts  and  hydrochloric  acid).  Only  60  per  cent., 
then,  of  cotton  is  nitrated  in  this  specimen ;  and  if  we 
compare  the  total  volume  of  nitrogen  dioxide,  126.8 
c.c.,  with  that  of  the  cotton  nitrated,  we  obtain 
214.7  c-c-  5  which  is  the  number  that  we  would  have 
found  if  the  reaction  were  allowed  to  proceed  to  com- 
pletion. 

This  method  of  dipping  preserves  the  cotton  fibre 
intact,  which  may  be  of  importance  in  relation  to  the 
manufacture  of  nitro  hunting  powders,  for  it  produces 
a  natural  and  absolutely  intimate  mixture  of  gun-cot- 
ton and  ordinary  cotton.  Moreover,  the  nitrated 
material  obtained  in  this  mixture  does  not  differ  at  all 


94  SMOKELESS   POWDER 

from  ordinary  gun-cotton,  and  we  may  hope  that  it 
possesses  a  stability  equal  to  that  of  the  latter. 

V.    RESUME   AND   CONCLUSIONS 

Composition  and  formula  of  nitro-cellulose. — The 
first  degree  of  complete  nitration  which  the  above-indi- 
cated reactions  allow  us  to  determine  corresponds  to 
a  yield  of  108  c.c.  of  nitrogen  dioxide  per  gram,  ap- 
proximately. This  reaction  is  produced  with  pure 
nitric  acid  and  three  equivalents  of  water.  It  is  slow, 
and  only  gives  a  small  yield,  on  account  of  the  cotton 
being  attacked  under  the  hydrating  influence  of  the 
acid,  which  is  then  the  principal  phenomenon. 

As  the  concentration  of  the  acids  is  increased,  the 
per  cent,  of  nitration  appears  to  advance  progressively 
to  128  c.c. ;  at  least  this  is  what  the  nitrogen  content 
of  specimens  12  and  13  of  the  first  series  (page  83) 
would  appear  to  show. 

It  would  be  well,  however,  to  maintain  a  certain 
reserve  upon  this  point,  because  since  these  products 
are  insoluble  in  the  solvents,  the  iodine  reaction  re- 
mains as  the  only  index  of  complete  nitration ;  and  it 
is  to  be  feared  that  certain  traces  of  incompletely 
nitrated  products  lower  the  percentage  of  mean  nitra- 
tion. 

From  128  c.c.  the  percentage  of  nitration  rises  by 
marked  increases  to  140  c.c.,  then  to  165  c.c.,  and 
finally  to  180  c.c.  Then,  as  the  concentration  of 
acid  increases,  the  percentage  of  nitration  rises  pro- 
gressively, by  insensible  degrees,  to  the  limit  corre- 
sponding to  military  gun-cotton,  which  yields  215  c.c. 


TH£  NITRATION  OF  COTTON  95 

In  this  last  period,  although  there  is  no  brisk  change 
in  the  percentage  of  nitration,  we  may  note  the  very 
clear  transition  point  at  190  c.c.  and  195  c.c.,  corre- 
sponding to  the  limit  of  the  zone  of  the  collodions. 

In  order  to  account  completely  for  the  different 
changes  by  the  production  of  nitro-products  corre- 
sponding to  definite  formulae,  it  is  necessary  to  quad- 
ruple the  equivalent  of  cellulose.  The  nitro-celluloses 
which  this  formula  leads  to  correspond  to  the  theo- 
retical yields  of  nitrogen  dioxide  per  gram  of  material 
indicated  in  the  following  table,  and  with  which  we 
compare  the  percentages  of  limiting  nitration  ob- 
served, corresponding  to  the  discontinuities  of  which 
we  have  spoken  already,  or  else  to  a  change  in  physi- 
cal properties: 

Theory        ment 

C24H29O20^NO2)i1.  .Cellulose  endecanitrate   )  _  j  214  c.c.        215  c  c. 

C24H30O20(NO2),0.  Cellulose  decanitrate..    ' 
C24H31O20(NO2)9 . .  .Cellulose  enneanitrate 
C24H32O20(NO2)8..  .Cellulose  octonitrate. . 
C24H33O20(NOa)7... Cellulose  heptanitrate. 
C24H34O20(NO,)6.  .-Cellulose  hexanitrate. 


C24H36O20(NO2)6.  ..Cellulose  pentanitrate 


I  Collodions. ...  •) 


203  215 


V  Friable  cottons  •<  146 
)  I  128 


192 
182 
164 


132 
109 


C24H  39O20(NO2)4 . . .  Cellulose  tetranitrate 108 

It  will  be  seen  that  these  formulae  take  suitable  ac- 
count of  the  production  of  limits  of  nitration  and  of 
all  particulars  presented  by  the  reaction. 

The  approximate  results  obtained,  however,  are 
always  lower  than  the  exact  volumes  of  nitrogen  by 
about  Y^J-.  The  differences  appear  to  be  attributable 
to  the  presence  of  a  very  small  quantity  of  products 
of  lower  nitration. 

Properties  of  nitro-celluloses. — The  explosive  prop- 
erties of  nitro-celluloses  are  in  direct  relation  to  the 


96  SMOKELESS  POWDER 

percentages  of  nitration.  As  the  nitration  diminishes 
the  vivacity  of  combustion  in  open  air  decreases,  and 
the  production  of  carbonaceous  residue  becomes  more 
marked.  We  may  thus  classify  at  a  glance  nitrated 
celluloses  in  one  of  three  groups — gun-cottons,  collo- 
dions, or  friable  cottons.  The  measurements  of  pres- 
sures developed  by  these  different  products  in  a  closed 
chamber  show  that  the  force  similarly  diminishes  with 
the  percentage  of  nitration.  Thus  a  collodion-cotton 
yielding  184  c.c.  produces  pressures  inferior  by  -J-  to  the 
pressure  furnished  by  Moulin-Blanc  gun-cotton  afford- 
ing 21 1  c.c.  The  percentage  of  nitrogen  constitutes 
a  true  measure  of  the  explosive  qualities  of  a  product. 

Finally,  we  may  mention  that  the  stability  of  nitro- 
celluloses  decreases  with  the  percentage  of  nitration, 
with  respect  to  reagents  such  as  hydrochloric  acid 
and  ferrous  salts.  For  products  of  low  nitration  the 
reaction  commences  when  cold ;  for  those  of  mean 
nitration  a  few  moments'  heating  is  required,  but  for 
celluloses  yielding  more  than  200  c.c.  of  nitrogen 
dioxide  per  gram,  the  attack  commences  only  after 
sustained  ebullition.  These  products  appear  then  to 
acquire  the  maximum  of  stability  along  with  the  maxi- 
mum of  power. 

PARIS,  September,  1883. 


APPENDIX    II 

PYROCOLLODION   SMOKELESS    POWDER 

By  Professor  D.  MENDELEEF 

(Translated  from  the  Russian  by  Lieutenant  John  B.  Bernadou 
U.  S.  Navy) 

THE  very  favorable  results  obtained  with  pyro- 
collodion,  and  its  adaptability  to  arms  of  all  calibres, 
depend  upon  its  composition  and  properties,  which, 
for  purposes  of  illustration,  may  be  compared  with 
those  of  other  materials  employed  as  smokeless  pow- 
ders. 

As  to  its  chemical  composition,  pyrocollodion  may 
be  designated  homogeneous,*  and  herein  consists  one  of 
its  most  important  qualities.  All  previous  and  pres- 
ent forms  of  powder  did  not  have  or  do  not  have  this 
property  to  the  degree  here  implied.  From  their 
very  method  of  preparation,  black  and  brown  powders 

*  Homogeneity,  in  its  full  chemical  significance,  is  not  claimed, 
inasmuch  as  the  composition  of  cellulose  itself  remains  a  matter 
of  doubt.  The  quality  is  urged  from  the  technical  standpoint,  in 
relation  to  the  properties  of  other  smokeless  powders.  It  is  pos- 
sible that  a  solvent  may  be  found  capable  of  separating  pyro- 
collodion fractionally;  but  pyrocollodion  insoluble  in  ether  or 
alcohol,  but  soluble  in  a  mixture  of  these  substances,  is  far  more 
homogeneous  than  other  forms  of  nitro-cellulose  or  any  of  the 
nitro-glycerin  powders,  inasmuch  as  the  latter  are  readily  capable 
of  fractional  subdivision. 

97 


98  SMOKELESS  POWDER 

are  coarse  mechanical  mixtures,  for  which  any  consid- 
eration of  homogeneity  is  out  of  the  question.  The 
same  is  true  for  those  smokeless  powders  containing 
ammonium  nitrate,  picrates,  etc.  Nitro-glycerin 
powders  may  be  regarded  as  gelatinous  solutions  of 
nitro-cellulose  in  nitro-glycerin,  which,  from  their 
composition,  are, chemically,  non-homogeneous;  more- 
over, various  solvents  (alcohol,  ether,  acetone,  etc.) 
dissolve  certain  constituents  out  of  them,  leaving 
others. 

The  same  may  be  said  of  present-day  types  of  nitro- 
cellulose powders ;  alcohol  dissolves  out  of  them  the 
nitro-celluloses  of  lower  nitration ;  a  mixture  of  ether 
and  alcohol,  the  collodions,  leaving  the  excess  of 
highly  nitrated  cellulose  undissolved.  Pyrocollo- 
dion,*  however,  surrenders  no  part  of  its  substance  to 
alcohol,  while  it  is  wholly  soluble  in  a  mixture  of 
ether  and  alcohol.  This  chemical  homogeneity  of 
pyrocollodion,  taken  in  the  sense  in  which  it  is  stated 
to  be  employed,  plays  an  important  role  in  its  com- 
bustion ;  for  there  are  many  reasons  for  believing  that 
in  the  case  of  the  combustion  of  those  physically  but 
not  chemically  homogeneous  substances,  such  as  the 
nitro-glycerin  powders  (ballistite,  cordite,  etc.),  the 
nitro-glycerin  portion  is  decomposed  first,  and  the 
nitro-cellulose  portion  burns  subsequently,  in  a  differ- 
ent layer  of  the  powder:f  It  is  to  be  added  that  the 

*  Under  the  assumption  that  the  remainder  of  the  solvent  is 
wholly  expelled  from  the  powder. 

f  The  experiments  of  Messrs.  I.  M.  and  P.  M.  Tcheltsov  at  the 
Scientific  and  Technical  Laboratory  show  that  for  a  given  density 


PYROCOLLODION    SMOKELESS  POWDER         99 

homogeneity  of  pyrocollodion  possesses  a  direct  bear- 
ing upon  the  uniformity  of  ballistic  results  developed 
by  its  use. 

Besides  chemical  homogeneity,  pyrocellulose  and 
the  powders  prepared  therefrom  possess  a  second  dis- 
tinguishing quality,  viz.,  that  for  a  given  weight  of 
their  substance  they  develop  a  maximum  volume  of 
evolved  gases,  the  latter  being  measured  at  a  given 
temperature  and  pressure.  This  new  conception  in- 
volves certain  intricacies  and  complexities,  and  may  be 
discussed  to  some  degree  of  fulness,  in  what  relates  to 
nature  and  volume  of  gases  evolved  upon  the  decom- 
position of  powder. 

According  to  the  law  of  Avogadro-G£rard,  *  the 
chemical  equivalents  or  quantities  of  matter  expressed 
by  simultaneous  chemical  formulae  (e.g.,  HaO  =  18, 
water;  CO  =  28,  carbonic  oxide;  CO2  =  44,  carbonic 
acid;  N2  =  28,  nitrogen)  occupy  at  a  given  temper- 
ture  and  pressure  a  volume  equal  to  that  occupied  by 
two  parts  by  weight  of  hydrogen,  Ha  =•  2  (its  molecu- 
lar equivalent).  Consequently,  if  we  possess  the  full 
chemical  equation  of  combustion  of  a  substance  or 

of  loading,  the  composition  of  the  gases  evolved  by  nitro-glycerin 
powders  varies  according  to  the  surface  area  of  the  grains  (i.e., 
the  thickness  of  strips  or  cords),  a  phenomenon  not  to  be  ob- 
served in  the  combustion  of  pyrocollodion  powder.  There  is 
only  one  explanation  for  this,  viz.,  that  the  nitro-glycerin,  which 
possesses  the  higher  rate  of  combustion  (Berthelot),  is  decom- 
posed sooner  than  the  nitro-cellulose  dissolved  in  it.  This  is  the 
reason  why  the  nitro-glycerin  powders  destroy  the  inner  surfaces 
of  gun-chambers  with  such  rapidity. 

*  The  development  of  this  law  is  given  in  "  Principles  of  Chem- 
istry," by  D.  Mendeleef,  6th  ed.,  1895,  chap.  7. 


IOO  SMOKELESS  POWDER 

mixture  of  substances,  of  which  the  products  are 
gases  or  vapor,  it  is  easy  to  calculate  the  volume 
occupied  by  these  products  at  a  given  temperature 
and  pressure.  For  example  :  the  combustion  of  black 
powder  may  be  expressed  typically  by  the  equation : 

2KNO.+  S   +  3C         =K3S  +  3COa  +  N2. 
Mol.  wt,  2  X  101  +  32  -{-3  X  12  =  110  +  3X44+28=270. 
Volume  in  form  of  gases,  3X2  +  2  =  8. 

That  is,  for  270  parts  by  weight  of  powder  ingredients 
8  volumes  of  gas*  are  formed,  or  29.6  volumes  per 

*  If  the  weights  of  the  equivalents  be  expressed  in  grams  we 
may  ascertain  the  volume  of  gas  evolved  in  litres,  when  the  pres- 
sure P  (in  millimeters  of  the  mercurial  column)  and  the  temper- 
ature /  (in  degrees  Celsius)  are  known.  Thus  as  two  equivalent 
weights  of  hydrogen  and  the  equivalent  of  each  gas  occupy  at  a 
temperature  t  =  o  and  a  pressure  P  =  760  mm.  a  volume  of  2?£ 
litres,  then  for  /  and  P  this  volume  becomes 

22*  (i  +  0.00367  /)  25°. 

Consequently  one  volume,  expressed  in  grams,  occupies,  approx- 
imately, 

11.1+0.4070*  litreSf 

/ 
where/  corresponds  to  the  number  of  atmospheres,  each  of  760 

p 
mm.  ato°C. ;  i.e., /  =  -;—.   Thus,  in  our  example,  if  t  =  2000°  C.  and 

p  =  2500  atm.,  the  8  volumes  of  gas  produced  by  the  combustion 
of  270  grams  of  powder  occupy  an  actual  volume  of 

g<  11.1+0.0407.2000  =         fi  Htre> 

2500 

At  o°  C.  and  a  pressure  of  i  atmosphere  we  attain  a  volume  of  88.8 
litres  for  270  grams.  In  this  manner  it  is  easy  to  proceed  to  the 
value  ^1000  given  in  the  text,  the  actual  volume  of  evolved  gases 
per  kilogram  of  powder. 


PYROCOLLODIOK  SMOKELESS  POWDER         IOI 

1000  parts  by  weight  of  explosive.  Brown  powder 
(cocoa)  represents  (in  its  greater  progressiveness  of 
combustion  and  in  certain  other  respects)  a  partial 
transformation  from  black  to  smokeless  powders,  and 
is  characterized  by  the  partial  carbonization  of  its 
charcoal  (which  contains  much  hydrogen  and  approx- 
imates to  a  composition  C6H4O),  and  by  the  small 
quantity  of  sulphur  entering  into  its  composition.  Its 
mode  of  combustion  may  be  expressed  approximately 
as  follows: 


6KN01+2C6H40=3KSCO,+7CO 

6X  101  +  2  X  80  =  3X138  +  7X28+4X18+3X28=766. 
Volume  of  gases,  7X2  +4X2  +3X2  =28. 

^,«  =  36.5- 

Or  as  follows  : 

4KN03+C5H40+S=K2S04+K2C03+4CO+2H20+2N2, 
Mol.  wt.  =  516,  Volume  of  gases  =  16, 

^,..,  =  31. 

It  is  evident,  then,  that  the  gas  volume  correspond- 
ing to  brown  powder  is  nearly  34,  —  greater  than  that 
for  black  powder;  whence  originates  the  preference 
generally  accorded  to  brown  powder  over  black. 

In  a  similar  manner  we  have  for  the  complete 
(typical)  combustion  of  nitro-glycerin, 

4C3H6N309  =  i2C03     +  ioH30  +  6N3    +  O,. 
Mol.  wt,  4  X  227  =  12  X  44  +  10  X  18  +  6X28+32  =  908 
Volume  of  gases  =  12X2    +10X2+6X2+2=58. 

^ooo  =  63.9- 

If  we  present  in  the  same  manner  the  decomposi- 
tion of  a  type  of  nitro-cellulose  of  high  nitration,  such 


IO2  SMOKELESS  POWDER 

as  Abel's  trinitro-cellulose,  C6H7(NO3)3O6,  we  obtain 
the  following: 

2C.H,N101I  =  sCO,     +9CO     +  7H20-f3N2. 
Mol.  wt.,  2  X  297  =  3  X  44+  9  X  28  +  7  X  18+3  X  28  — 594. 
Volume  of  gases  =  3X2    +9X2   -{-7  X  2   +3  X  2    =44. 

^,000  =  74-1- 

If  the  typical  combustion  of  this  nitro-cellulose  be 
presented  by  the  equation 

2C6HtN.On  =  ioCOa  +  2CO  +  7H,  +  3N3 , 

that  is,  if  we  assume  that  water  is  not  formed,  and 
that  the  oxygen  combines  wholly  with  the  carbon, 
then  the  F,000  remains  unchanged,  as  the  volume  of 
gas  formed  (22X2=  44)  remains  as  before.  Therefore 
we  need  not  stop  to  consider  how  the  oxygen  is  dis- 
tributed between  the  carbon  and  hydrogen  in  the 
products  of  combustion,  as  the  value  of  F"1000  does  not 
vary.* 

If,  for  nitro-cellulose  of  high  nitration  we  substitute 
Eder's    pentanitro-cellulose,    C12H16(NOa)6O10,     which 

*  It  is  another  matter  if  a  portion  of  the  oxygen  continues  in 
combination  with  the  nitrogen,  or  if  the  oxygen  proves  insuffi- 
cient to  convert  all  the  carbon  and  hydrogen  into  gases;  that  is, 
if  hydrocarbons  are  formed;  but  this  becomes  a  case  of  incom- 
plete combustion.  Such  conditions  have  a  certain  bearing  upon 
the  combustion  of  smokeless  powders,  especially  when  the  sol- 
vent is  not  completely  expelled;  but,  on  the  one  hand,  the  quan- 
tity of  hydrocarbons  formed  is  relatively  small,  and  on  the  other, 
they  are  formed  (as  also  compounds  of  carbon  and  nitrogen,  as 
cyanogen),  in  relatively  small  quantities,  for  all  powders,  even 
when  the  latter  contain  an  excess  of  oxygen.  In  considering 
type  forms  of  combustion  there  is  no  need  of  investigating  second- 
ary conditions  of  this  class,  especially  as  by  so  doing  we  are 
diverted  from  the  direct  study  of  the  general  problem. 


PYROCOLLODION  SMOKELESS  POWDER         IO3 

corresponds  to  a  content  of  12.75  Per  cent,  nitrogen, 
and  to  the  composition  of  ordinary  nitro-cellulose 
employed  for  smokeless  powders,  we  obtain  a  greater 
evolution  of  gas,  for 

2C12HlbN60,0  -  CO,  +  23CO  +  i5H,0  +  5N.. 
Mol.wt.,  2X549-  44+  23  X  28 .+  15  X  18+5X28=1098. 
Volume  of  gases  =  2     +  23.2        -j-  15.2        +5.2       =  88. 

r»n  =  80. i.  ' 

The  increase  in  volume  of  gas  hereby  realized  is  due  to 
the  fact  that  the  quantity  of  carbonic  acid  evolved  is 
diminished,  while  that  of  carbonic  oxide  is  increased, 
which  causes  an  increase  of  total  gas  volume,  since, 
for  the  equation 

C  +  0.  =  CO,,  riM.=45-55 

and  for  the  equation 

C  +  0  =CO,    F1000  =  7i.4. 

If  we  descend  to  a  lower  nitration  and  consider 
Eder's  tetranitro-cellulose,  C12H18(NO,)4O,0,  we  have 
no  longer  the  case  of  complete  combustion;  for  20 
equivalents  of  oxygen  are  required  to  convert  12  of 
carbon  and  16  of  hydrogen  into  gaseous  products  and 
vapors,  while  there  are  but  18  of  oxygen  available,  un- 
less we  assume  the  products  of  combustion  as  CO, 
H,O,  and  H9.*  It  is  known,  however,  that  in  the  case 

*In  the  latter  case  (without  formation  of  carbon)  the  decompo- 
sition would  be: 

C)aH16N4018=  I2CO      +  6H30+2Ha     +  2Na. 
Mol.  wt.,  504  =  12  X  28  +  6  X  18  +  2  X  2  +  2  Xj28  =  504. 
Volume  of  gases  =  12X2    +6X2    +2X2  +  2X2    =44. 

r.ooo  =  87.5. 

But  typical  combustion,  according  to  such  an  equation,  is  prac- 
tically impossible;  carbon  and  hydrocarbons  are  formed,  and  the 

|  UNiV£R? 


104  SMOKELESS   POWDER 

of  combustion  of  carbohydrates  low  in  oxygen,  the 
latter  combines  with  the  hydrogen,  from  its  greater 
affinity  for  that  substance,  leaving  a  part  of  the  carbon 
deposited  in  an  uncombined  state.  Consequently,  such 
conditions  do  not  correspond  to  complete  combustion. 
The  formation  of  CO,  shows  that  there  is  a  certain 
excess  of  oxygen  in  pentanitro-cellulose ;  whereas 
typical  combustion,  corresponding  to  maximum  gas 
volume,  requires  all  carbon  to  be  converted  into  car- 
bonic oxide.  Such  typical  combustion  is  afforded  by 
pyrocollodion,  the  composition  of  which  corresponds 
to  the  formula  C80H98NjaO49,  as  is  shown  by  the  follow- 
ing equation : 

5C.H..O.  +  I2HNO,  =  C,.H,,(NO.)1101.  +  "H.O. 

Cellulose  Nitric  Acid  Pyrocellulose  Water 

combustion  that  actually  does  occur  is  intermediate  in  character 
to  that  expressed  by  the  above  and  by  the  two  following  equa- 
tions : 

2CiaH18N4O,8  =  C4  -f-  2oCO  -f  i6HaO  +  4Na. 
2CiaH19N4018  =  22CO  -f  i4HaO  +  CaH4  +  4Na. 
For  the  first,  Kiooo  =  79-45  for  the  second,  81.4;  the  mean  of 
the  two  latter  is  80.4;  of  all  three,  82.4.  This  quantity  is  close  to 
that  afforded  by  pentanitro-cellulose  and  pyrocollodion.  In  this 
manner  may  be  explained  the  phenomenon  that  upon  the  combus- 
tion of  nitro-cellulose  containing  a  little  less  than  12.5  per  cent, 
nitrogen,  or  of  pyrocollodion  containing  a  certain  quantity  of  un- 
evaporated  solvent  (which  is  equivalent  to  a  lowering  of  nitra- 
tion), results  are  obtained  that  approximate  to  those  produced  by 
pyrocollodion  powder,  although  velocities  and  pressures  are 
somewhat  lowered.  The  existence  of  this  phenomenon  depends 
upon  the  homogeneity  of  the  powder;  whence  it  follows  that  it  is 
better  to  have  a  content  of  a  little  less  than  12.5  per  cent,  nitrogen 
with  a  homogeneous  powder  than  a  content  of  above  12.5  per  cent, 
with  the  powder  non-homogeneous,  and  that  the  best  results  are 
developed  by  homogeneous  pyrocollodion  of  nitration  N  =  12.4 
per  cent. 


PYROCOLLODION  SMOKELESS   POWDER          IO$ 

In  typical  combustion  it  corresponds  to  the  follow- 
ing equation  : 

CSOH38N12048  =  3oCO  +  i9H20+6Nr 

Mol.  wt.,  1350       —  30X28+19  Xi8  +  6  X  28  =  1350. 

Volume  of  gases  =30X2   +19  X2+6X2     =  no. 

Before  proceeding  further,  we  desire  to  call  atten- 
tion to  the  fact  that,  whereas  for  brown  powder  we 
realize  a  volume  of  34  approximately,  we  have  here  a 
volume  of  81.5,  whence,  judging  from  volumes  of 
evolved  gases,  pyrocollodion  should  prove  2j  times 
more  powerful  than  brown  powder.  Actual  experi- 
ments show  that  the  powders  stand  in  about  'this  rela- 
tion to  one  another.  In  units  of  energy  per  unit  for 
weight  of  explosive  we  have 

Pyrocollodion  Brown  Ratio 

powder  powder 

47  m.m.  R.  F.  about      220  81.5  2.7:1 

9-in.  gun,  "          223  90.7  2.5  :  I 

12-in.  gun,  "          210  93  2.3:1 

From  this  it  is  evident  that  our  computed  value  of 
F"loou  is  in  complete  accordance  with  actual  experimental 
results. 

In  this  manner  we  may  consider  it  as  proven  that, 
for  a  given  temperature  and  pressure,  pyrocollodion 
develops  a  greater  volume  of  gases  (and  vapor)  than  is 
developed  by  black  or  brown  powder  (for  which 
J^iooo  =  3°)>  and  even  greater  than  is  afforded  by  pow- 
ders prepared  from  the  more  Jiighly  nitrated  forms  of 
nitro-cellulose,  and  by  the  nitro-glycerin  poivders* 

*  The  rapid,  simple  and  novel  method  of  comparing  the  force  of 
explosives   herein  employed  was   first  suggested  and   used  by  me 


106  SMOKELESS  POWDER 

In  order  to  establish  the  full  significance  of  the 
above  deduction,  it  remains  to  show  (i)  that  from  the 
standpoint  of  practical  applicability  we  can  foresee  no 
other  material  capable  of  developing  as  great  a  value 
for  F1000  as  pyrocollodion ;  (2)  that  the  physico-chem- 
ical and  ballistic  qualities  necessary  in  a  smokeless 
powder  are  developed  by  pyrocollodion,  not  in  a  less, 
but  in  an  equal  or  greater  degree  than  by  other  mate- 
rials employed  as  smokeless  powders;  (3)  that  the 
estimate  of  ballistic  efficiency  of  a  smokeless  explosive, 
through  consideration  of  its  volume  of  evolved  gas, 
without  regard  to  conditions  of  temperature,  leads  us 

in  1892.  It  was  developed  through  comparison  of  the  composition 
of  smokeless  powders  and  of  their  products  of  combustion  and  of 
the  results  of  experimental  firings  made  at  the  laboratory.  Al- 
though I  see  clearly  that  not  only  the  volumes  of  products  of 
combustion,  but  also  their  temperatures,  must  be  taken  into 
account  in  a  complete  analysis  of  phenomena  attending  the 
decomposition  of  smokeless  powders,  nevertheless  I  purposely 
give  preference  in  these  investigations  to  phenomena  relating  to 
volumes  of  gases  evolved,  not  only  on  account  of  the  simplicity 
of  the  latter  and  their  direct  accordance  with  ballistic  results,  but 
for  the  reason  that  with  present  methods  for  estimating  tempera- 
tures developed  by  explosives  (and  these  methods  are  unreliable) 
it  becomes  necessary  to  make  numerous  arbitrary  assumptions 
(especially  in  relation  to  specific  heats  of  gases  and  vapors  at  high 
temperatures);  while  for  volume  calculations  we  have  definiteness 
of  composition  as  a  starting  point;  and  if  there  be  any  assump- 
tion to  be  made,  it  relates  to  the  distribution  of  the  oxygen  be- 
tween the  carbon  and  hydrogen,  which,  from  the  chemical  stand- 
point, is  not  so  material — and  so  far  as  it  relates  to  volume  it 
is  of  little  significance.  In  all  cases,  however,  I  present  but  the 
elementary  comparisons  of  performances  of  powders,  as  the  fuller 
treatment  of  the  subject  does  not  constitute  the  object  of  my 
investigation. 


PYROCOLLODION-  SMOKELESS   POWDER         IO/ 

into  no  error,  although  it  would  at  first  appear  that 
temperature  would  have  a  direct  effect  upon  the  prac- 
tical qualities  of  a  powder. 

Since  smokeless  powder  was  discovered,  so  many 
schemes  were  set  afloat  for  meeting  general  demands, 
that  up  to  the  present  time  there  remain  as  open 
questions  which  form  of  smokeless  powder  is  the 
superior,  and  whether  new  and  still  more  efficient  forms 
may  not  be  looked  for  in  the  future.  In  order  to  re- 
ply to  these  inquiries,  it  will  be  necessary  first  to  glance 
over  the  compositions  of  materials  capable  of  conver- 
sion into  smokeless  powders  under  the  following  as- 
sumptions: (i)  That  they  leave  no  solid  residue  after 
combustion,  and  that  their  gases  exercise  no  injurious 
effect  upon  the  metal  of  guns  ;  (2)  that  they  undergo 
no  change  upon  keeping  for  long  periods  of  time,  and 
contain  no  volatile  ingredients  ;  and  (3)  that  they  may 
be  readily  prepared  in  quantities  sufficiently  abundant 
for  practical  needs. 

There  are  but  few  elements  capable  of  producing 
gases  that  do  not  act  upon  metals,  and,  generally 
speaking,  it  is  useless  to  try  to  find  others  besides 
hydrogen  and  nitrogen,  and  their  compounds  with 
oxygen  and  carbon,  that  do  not  act  upon  gun-cham- 
bers at  the  temperatures  of  combustion  of  powder. 
Therefore,  in  general  terms,  the  composition  of  those 
mixtures  or  compounds  suitable  for  conversion  into 
powder  may  be  expressed  as 


The  energy  imparted  to  the  projectile  is  derived  from 


1O8  SMOKELESS   POWDER 

the  conversion  of  the  mass  of  the  powder  into  gases, * 
the  transformation  being  accompanied  with  the  pro- 
duction of  great  heat.  These  fundamental  conditions 
serve  to  limit  the  number  of  materials  that  are  capable 
of  conversion  into  smokeless  powder,  the  limitations 
arising  not  only  from  the  above-named  practical  re- 
quirements, but  also  from  the  chemical  impossibility  of 
existence  of  many  bodies  which,  if  obtainable,  would 
decompose  in  the  manner  requisite  for  efficient  ballis- 
tic action.  Thus,  e.g.,  there  does  not  exist,  nor  can 
we  look  forward  to  the  existence  of,  such  a  polymer 
(in  the  solid  or  liquid  form)  of  hydrogen  as  H«  ,  which 
would  decompose  into  hydrogen,  Ha ,  with  a  corre- 
sponding production  of  heat.f 

If  we  may  not  look  for  explosives  among  the  sim- 
plest chemical  combinations  of  the  elements,  we  may 
perhaps  find  them  among  those  compounds  of  nitro- 
gen and  hydrogen  which  stand  in  the  same  relation  to 
ammonia,  NH3,  as  the  hydrocarbons  do  to  methane, 

*  And  is  not  derived  from  an  external  source  of  energy,  such  as 
the  tension  of  a  spring  or  the  physical  compression  of  gases,  as 
in  the  Giffard  gun. 

f  If  such  a  substance  existed,  then  its  decomposition,  according 
to  the  equation  Ha«  =  wHa,  would  afford  a  weight  2«  for  a  volume 
2«;  that  is,  Fiooo  would  be  equal  to  1000,  the  greatest  possible 
value.  For  nitrogen  under  similar  conditions  we  would  have 
Fiooo  =  71.4,  or  less  than  for  pyrocollodion.  But  the  existence 
of  such  a  polymer  is  highly  improbable.  If  argon  (vid.  Mende- 
leef,  "  Principles  of  Chemistry,"  6th  ed.,  1895,  p. 749)  were  the  poly- 
mer of  nitrogen,  N3,  its  conversion  into  nitrogen  could  only  be 
accomplished  through  the  absorption  of  heat;  i.e.,  it  would  find  no 
place  in  the  category  of  "  explosive  "  bodies  (to  which  ozone  pos- 
sesses a  relation). 


PYROCOLLODION  SMOKELESS  POWDER        IOQ 

CH4.  We  should  thus  have,  corresponding  to  ammo- 
nia, the  series  NMHw  +  2  (e.g.,  diamide  N2H4;  triamide 
N3H6;  etc.)  and  the  series  NMHM,  NMHw_a,  etc.  As 
the  representative  of  the  latter  we  have,  for  n  =  3,  the 
nitro-hydric  acid  of  Curtius,  N3H,  which  actually  is  a 
very  explosive  body,  and  which  forms  salts,  e.g.,  with 
ammonium  N3(NH4)=  N4H4,  which  is  also  explosive, 
decomposing  into  the  gases  nitrogen  and  hydrogen 
with  the  evolution  of  heat,  although  ammonia  itself  is 
not  susceptible  of  explosive  decomposition,  but  ab- 
sorbs heat  in  the  reaction.  If  such  compounds  could 
be  easily  prepared,  and  if  they  possessed  the  qualities 
necessary  to  an  efficient  smokeless  powder,  such  as 
non-volatility,  good  keeping  quality,  progressiveness 
in  combustion,  etc.,  they  would  prove  especially  suit- 
able for  conversion  into  smokeless  powders,  as  the 
corresponding  values  of  F"1000  would  be  greater  than 
for  other  powders.  Thus  we  should  have  for  nitro- 
hydric  acid, 

2N3H  =  H3+3N,. 
Mol,  wt.     2X43=    2+3x28=86. 
Volume  of  gases,        2  +  3X    2  =  8. 
PI..O  =  93-0. 

For  NWHM  the  volume  would  be  still  greater,  as 
F1000  =  133.3.  But  even  if  such  products  could  be  con- 
veniently prepared  from  readily  procurable  materials  it 
would  be 'useless  to  consider  them  as  available  for 
conversion  into  smokeless  powders,  for  the  reason 
that  they  do  not  decompose  through  gradual  or 
progressive  combustion,  which  is  indispensable  in  a 


HO  SMOKELESS   POWDER 

smokeless  powder,  but  detonate  or  decompose  with 
extreme  suddenness;  hence,  while  they  might  prove 
suitable  for  filling  mines  or  shells,  they  are  unadapted 
for  use  in  cannon.  This  property  of  progressive  com- 
bustion or  decomposition  in  successive  strata  is  pos- 
sessed only  by  those  substances  containing  both  com- 
bustible ingredients,  and  ingredients  capable  of  effect- 
ing progressive  combustion,  such  as  carbon  and 
hydrogen,  which  are  consumed  by  the  oxygen  held  in 
close  proximity  to  them  but  which  is  not  in  direct 
combination  with  them. 

The  "combustion"  of  a  powder  is  the  union  of 
the  carbon  and  hydrogen  of  the  mixture  or  com- 
pound with  the  oxygen  that  it  contains,  and  with 
which  it  is  in  association,  but  not  in  direct  combina- 
tion. From  what  has  been  said  already,  it  is  evident 
that  if  the  powder  is  to  be  smokeless  and  produce  the 
maximum  volume  of  gas,  F1000,  it  must  evolve  no 
other  gases  than  carbonic  oxide,  CO,  water  vapor, 
H9O,  and  nitrogen,  Na.  If  hydrogen  be  evolved,  with- 
out the  formation  of  the  corresponding  quantity 
(equal  volume)  of  carbonic  acid,  free  carbon  may  re- 
sult, i.e.,  the  powder  will  not  be  wholly  smokeless  on 
account  of  insufficiency  of  oxygen.  If  the  combus- 
tion, as  indicated  by  the  equation,  reveals  carbonic 
acid  or  free  oxygen  (without  the  corresponding  vol- 
ume of  hydrogen),  an  excess  of  oxygen  is  evident, 
and  F^ooo  will  not  possess  its  maximum  value. 

We  have,  therefore,  in  the  case  of  a  composition  or 
mixture  CMH2wN,?Or,  the  maximum  volume  F1000  for 
typical  smokeless  combustion,  corresponding  to  two 


P  YROCOLLODION  SMOKELESS  PO  WDER        \  1 1 

conditions:  (i)  When  the  content  of  oxygen,  r,  is 
just  sufficient  to  convert  the  carbon  into  CO,  and 
the  hydrogen  into  HaO,  i.e.,  when  r  =  n  -f-  m ;  (2) 
when  the  content  of  hydrogen  is  relatively  great,  as 
F1000  for  HaO  equals  iii.i,  i.e.,  more  than  for  nitro- 
gen and  for  carbonic  oxide,  for  which  F1000  =  ^f f- 
=  71.4.  Moreover,  all  substances  of  the  composition 
CHHtmNqOH+m  will  develop  volumes  between  71.4  and 
iii.i,  if  the  decomposition  products  be  CO,  N,  and 
HaO  alone,  as  is  required  for  rendering  F,000  a  maxi- 
mum. Our  problem  becomes,  therefore,  the  com- 
parative examination  of  those  bodies  rich  in  hydrogen, 
for  which  F"1000  may  be  greater  than  for  pyrocellulose 
(81.5).  We  must  ask:  Are  there  not  known  sub- 
stances, or  mixtures  of  substances,  rich  in  hydrogen 
suitable  for  smokeless  powder?  To  answer  this  query, 
let  us  examine  various  definite  compounds  and  mix- 
tures. 

Among  the  carbon  compounds  a  large  content  of 
hydrogen  is  characteristic  of  methane  (marsh  gas), 
CH4 ;  also  among  the  nitrogen  compounds,  or  the 
ammonium  derivatives. 

Hydrocarbons  of  the  limiting  (saturated)  series 
CwHaw_|_9*  form  nitro-compounds,  and  may,  therefore, 
produce  explosives.  To  methane  itself,  CH4,  there 
correspond  mononitro-methane,  CH,(NOa);  dinitro- 
methane,  CHa(NOa)a ;  trinitro-methane  or  nitroform, 
CH(NOa),,  and  tetranitro-methane  C(NOa)4.  These 


*  See   "The   Principles  of  Chemistry,"  by  D.  Mendeleef,  1891, 
Longmans,  Green  &  Co.,  London,  Vol.  I,  p.  344.     J.  B.  B. 


112  SMOKELESS  POWDER 

substances  are  volatile  as  well  as  explosive,  but  all 
represent  a  deficiency  or  an  excess  of  oxygen.  As 
shown  by  V.  Meyer  and  Professor  Zalinski,  the  ex- 
plosive properties  of  mononitro-methane  are  espe- 
cially great  when  it  is  combined  with  potassium  or 
sodium  to  form  the  metallic  salts,  CHaKNOa  and 
CH5NaNOa,  which  represent,  so  to  speak,  first  homo- 
logues  of  the  salts  of  nitric  acid,  since  CHaNaNOa 
—  NaNOa  equals  the  homologous  difference  CHa. 
Experiment  shows  that  this  substance  belongs  to 
the  category  of  detonating  explosives,  and  is,  there- 
fore, unsuitable  for  use  in  guns  (but  suitable  for 
mines). 

If  the  decomposition  proceeds  without  formation  of 
free  carbon  (although  there  be  but  little  oxygen),  it 
should  be  as  follows: 

2CH8NOa  =  2CO  +  2HaO  +  Ha  +  Na. 

If  it  be  thus,  then  F1000  =98.3,  which  is  very  great. 
But,  as  has  been  said,  the  substance  is  unfit  for  use  in 
guns  on  account  of  its  tendency  to  detonate.  Be- 
sides, like  other  nitro-methanes,  it  is  volatile,  and  for 
this  reason  is  further  unadapted. 

The  little  known,  but  doubtlessly  explosive,  dinitro- 
methane  contains  an  evident  excess  of  oxygen,  devel- 
oping on  combustion,  CO,  -f-  HaO  +  iOa+  Na,  which 
corresponds  to  the  relatively  small  volume  F1000  =  66. 
It  is  evident  that  the  excess  of  nitrogen  and  of  oxygen 
combined  with  it  in  the  NOa,  according  to  the  known 
principle,  does  not  increase  but  rather  diminishes 
F,009.  The  same  is  true  for  nitroform,  CH(NO,)3  = 


PYROCOLLODION  SMOKELESS  POWDER        113 

CHN3O8,*  and  for  tetranitro-methane,  the  discovery 
of  which  is  due  to  the  skill  of  our  eminent  savant, 
L.  N.  Shishkov.  Both*  of  these  substances  contain  too 
much  oxygen  to  develop  maximum  gas  volumes.  A 
large  value  of  F"looo  would  be  characteristic  of  mixtures 
of  products  of  nitration  and  of  hydration  (substituting 
the  water  radicle  for  hydrogen,  —  H+OH)  derived 
from  methane,  as : 

4CH.NO,  +  CH,N,04  -  5CO  +  ;H3O  +  3N,f 
Mol.  wt.,  4X61  +  io6=5X28+7X  18+3x28  =  350. 
Volume  of  gases,  5X2+7X2+3X2    =30. 

F1000  =  85. 
Or: 

Nitro-methane     Methyl  alcohol 

4CH,NO,+CH40  =  5CO  +8H,O+2N,. 
Mol.  wt.,  4  X  77+32  =  5x28+8 X  18+2x28  =  340. 
Volume  of  gases  =5X2  +8  X  2  +2  X  2    =30. 

F1000  =  88.2,  etc. 

But  such  mixtures,  although  possible  from  the  chem- 
ical standpoint,  are  unsuitable  for  use  as  powder,  be- 
cause their  constituents  are  in  part  volatile ;  and  this, 
apart  from  the  consideration  that  liquid  explosives  are 
prone  to  detonation,  which  is  more  to  be  dreaded  than 
formation  of  smoke,  as  detonation  destroys  the  guns. 

*  As  the  typical  decomposition  of  nitroform,  we  have — 

4CHN80,=4COa    +  70,     -f-2HaO  +  6Na. 
Mol.  wt.,  4  X  151  =4  X  44  +  7X32  +  2X18+6X28  =  604. 

Volume  of  gases  4  X  2   +7X2    +2X2    +6X2    =38. 
f  The  mixture  yCH4  -+-  3C(NO2)4  presents  such  a  composition, 
etc.,  but  such  mixtures  are  all  as  practically  unsuitable  for  pow- 
der as  mixtures  of  mono-  and  dinitro-methane. 


114  SMOKELESS  POWDER 

Among  the  closely  allied  derivatives  of  methane  as 
a  hydrocarbon  rich  in  hydrogen,  the  development  of 
a  large  gas  volume  may  be  looked  for  from  substances 
presenting  the  composition  CN3H6O4.  Such  a  com- 
position is  possessed,  for  example,  by  the  mixture 
of  a  molecule  of  formic  aldehyde,  CHaO  (or  of  one 
of  its  numerous  polymers),  with  ammonium  nitrate, 
NH4NO3,  or  the  hydroxyl  derivative  of  methylamine 
(i.e.,  CH,NHa  in  the  form  CHa[OH]NHa)  in  com- 
bination with  nitric  acid,  HNO3.  The  typical  de- 
composition of  such  a  compound,  if  realized,  would  be 
expressed  by  the  equation : 

CN3H604  =  CO+3HaO     +N3. 
Mol.  wt.,  1 10  =  28    +3  X   18  +  28  =  no. 

Volume  of  gases  —    2    +3X2    +    2  —  10. 
Fioo.  =  9.09. 

But  such  a  compound  either  cannot  be  produced,  or 
else  is  obtained  only  with  great  difficulty ;  or,  as  a  mix- 
ture of  ammonium  nitrate  with  the  polymers  of  formic 
aldehyde  (e.g.,  glucose,  C6HlaO6  =  6CHaO),  it  develops 
undesirable  qualities,  such  as  hygroscopicity,  a  charac- 
teristic of  all  mixtures  containing  ammonium  nitrate, 
and  is  therefore  unsuited  for  use  as  smokeless  powder. 

Hence,  after  searching  through  all  the  possible  com- 
binations of  the  simplest  derivatives  of  methane,  we 
are  unable  to  find  among  them  (as  also  among  sub- 
stances containing  no  carbon)  any  suitable  for  employ- 
ment in  practice  as  smokeless  powder,  although  we 
find  compounds  developing  larger  volumes  of  gas  than 
pyrocollodion,  and  which  may  prove  suitable  for  use 
in  mines. 


PYROCOLLODION  SMOKELESS  POWDER        11$ 

If  we  turn  from  substances  containing  one  atom  of 
carbon  to  those  with  two,  three,  etc.,  atoms  to  the 
molecule,  we  shall  find,  other  conditions  being  the 
same,  smaller  values  of  F"1000,  the  volume  decreasing 
the  farther  the  limit  is  departed  from,  as  is  illustrated 
in  the  following  table  of  possible,  little  volatile,  com- 
pound ethers  of  nitric  acid*  and  their  hypothetical 
nitro-compounds,  corresponding  to  the  series  of  alco- 
hols,  CwHaw(NOa), 

3C3H4(N03)a  +  2C.H.O,  F1000=  AV  1000=86.2 

C3H6(NO,)a  "     -  tto  1000=84.3 

QH8(N03)a  +  4C4H7(N02)(N03)a      "      =T«¥  1000=83.7 
C6H10(N03)a  +  4C6H8(NOa)a(NO,)a    '       =TWo  1000=82.7 


etc.,  etc. 

The  possible,  yet  up  to  the  present,  hypothetical, 
nitric  ethers  of  nitro-glucol,  although  capable  of  devel- 
oping large  values  of  VIOOQ,  and  adaptable  on  account 
of  their  non-volatility,  possess  no  advantages  over 
derivatives  of  the  higher  alcohols,  such  as  glycerin 
and  mannite,  materials  that  are  readily  obtainable 
as  they  are  widely  disseminated  throughout  nature. 
We  shall  therefore  fix  our  attention  upon  the  latter, 
first,  as  they  present  in  their  analogues  substances  ex- 
tremely rich  in  hydrogen,  capable  of  producing  large 
values  of  F1000  ;  and  second,  because  they  are  easily  re- 

*  Considered  by  themselves  these  ethers  of  diatomic  limiting 
(saturated)  alcohols  CWH2«(NO3)2  consume  into  CO  and  HaO  only 
for  n  =  3.  For  greater  values  of  n  there  is  a  deficiency  in  oxy- 
gen; for  n  =  2,  an  excess.  We  have  chosen  them  as  an  example 
on  account  of  their  slight  volatility,  and  because  they  approximate 
nitro-glycerin  and  nitro-mannite  in  composition. 


Il6  SMOKELESS  POWDER 

acted  upon  by  nitric  acid,  forming  the  explosive  com- 
pound ethers,  nitro-glycerin,  C8H5(NOS)3  —  CeH6N8Ofl , 
and  nitro-mannite,  C6H8(NO3)6Oe=:  C6H8N6O18.  Both  of 
these  nitro-derivatives  are  easily  prepared.  The  for- 
mer was  first  employed  as  an  explosive  by  the  re- 
nowned Russian  chemist  N.  N.  Zinin,  at  the  time  of 
the  Crimean  war,  and  subsequently  by  V.  F.  Petru- 
shevski,  in  the  sixties,  before  the  discovery  and  very 
general  employment  of  Nobel's  dynamite  and  other 
nitro-glycerin  preparations;  the  cause  of  their  gen- 
eral use  being  the  ease  with  which  the  base  material — 
glycerin — was  obtainable  in  nature,  while  the  reac- 
tion with  nitric  acid  (admixed  with  sulphuric)  was 
easily  effected,  i.e.,  the  manufacturing  process  was  a 
simple  one. 

Nitro-mannite,  isolated  and  investigated  by  N.  N. 
Sokolov,  professor  at  the  Medico-Chirurgical  Academy, 
is  also  easily  prepared,  but  not  in  its  lower  degrees  of 
nitration.  This  circumstance  is  important,  for  the 
reason  that  the  readily  manufactured  nitro-glycerin 
and  nitro-mannite  are  not  themselves  available  for  use 
in  guns,  although  very  well  adapted  for  detonating 
effects.  They  correspond,  moreover,  to  relatively 
small  values  of  F1000,  as  they  contain  an  excess  of 
oxygen : 

CsHt(NO,),  affords  F10M  =  63.9. 
C,H.(NO,).       "        F10M  =  6i.9. 

But  as  these  substances  contain  an  excess  of  oxygen, 
they  may  be  admixed  with  others  containing  a  defi- 
ciency thereof,  and  which  they  consume,  evolving  car- 


PYROCOLLODION  SMOKELESS   POWDER       I  I/ 

bonic  oxide  and  developing  relatively  large  volumes, 
Fj000  ;  while  by  admixture  with  such  substances,  low  in 
oxygen,  or  not  containing  it,  their  detonating  qualities 
may  be  caused  to  diminish,  or  made  to  vanish,  as  in 
dynamite,  by  combination  with  an  inert  base  (tripoli, 
magnesia,  etc.),  whereby  the  tendency  of  nitre-glyc- 
erin to  detonation  through  shock  is  diminished.  In 
this  manner,  by  admixture  with  a  combustible  sub- 
stance, nitro-glycerin  powders  are  formed.  If  we  take 
cordite  as  an  example,  we  find  that  on  account  of 
its  excess  of  oxygen  it  produces  a  relatively  small  gas 
volume  ;  we  may,  therefore,  select  a  mixture  of  nitro- 
glycerin  and  collodion  (assumed  as  CeH8[NOa]aO6) 
such  as  ballistite  and  determine  for  it  F"1000  on  the  as- 
sumption that  it  shall  develop  only  CO,  HaO  and  Nt. 


2C,H6N309+7CBH8N,09=48CO 

Mol.wt.  2X227+7  X  252=48X28+33X18+10X28  =  2218. 
Volume  of  gases  =48X2  +33X2  +10X2   =182. 


Therefore,  if  nitro-glycerin  powders  contain  only 
the  quantity  of  nitro-glycerin  necessary  to  produce 
HaO  and  CO,  then  the  volume  of  gases  evolved  by 
them  is  almost  the  same  as  that  developed  by  pyro- 
collodion.  It  is  evident,  then,  that  neither  nitro- 
glycerin  nor  its  mixtures,  when  employed  as  smoke- 
less powder,  evolve  volumes  of  gases  greater  than  pyro- 
collodion,  and  that  admixture  with  other  substances, 
of  whatever  kind  they  may  be,  although  homogeneous 
from  the  mechanical  standpoint,  are  still  far  less  homo- 
geneous than  any  single  substance,  and  that  it  is  use- 


Il8  SMOKELESS  POWDER 

less  to  seek  for  nitro-glycerin  powders  capable  of  ex- 
ceeding pyrocollodion  powders  in  point  of  magnitude 
of  f1000 ,  apart  from  other  considerations.  This  ap- 
plies also  to  nitro-mannite,  the  source  of  preparation 
of  which  is  far  less  common  than  glycerin,  and  to 
many  of  the  hydrocarbons  analogous  thereto,  as  glu- 
cose, starch,  cellulose,  etc.  If  all  of  the  six  atoms  of 
carbon  in  mannite  are  in  the  same  combination  as  in 
the  limiting  (saturated)  alcohols : 

*CH3(bH)CH(OH)CH(OH)CH(OH)CH(OH)CH,(OH), 

then  in  glucose,  C6H13O6,  one  atom  of  carbon  should 
be  combined  as  in  aldehyde, 

COH  CH(OH)CH(OH)CH(OH)CH(OH)CH,(OH), 

and,  therefore,  if  mannite  represents  a  hexanitrated 
product  (compound  ether  as  derived  from  an  alco- 
hol), glucose  represents  only  a  pentanitrate.  Mate- 
rials such  as  cellulose,  starch,  and  the  like,  of  compo- 
sition C8H10O6,  may  be  regarded  as  the  preceding  alco- 
hols— anhydrous,  arranged  as  follows  with  reference 
to  the  di-alcoholic  groups: 

CHCH, 

C.H1006  =  COH  CH(OH)  CH(OH)  CH(OH)  — , —  , 

O 

whereby  it  appears  that  there  are  only  three  com- 
plete alcohol  groups  remaining  out  of  the  six  in  man- 
nite. Therefore,  in  the  latter  case,  we  should  expect 
to  find  only  trinitrated  products,  which  is  actually 
what  occurs,  If  such  a  scheme  throws  light  on  the 


PYROCOLLODION  SMOKELESS  POWDER        I  IQ 

matter  from  one  standpoint  (as  relates  to  the  number 
of  hydroxyl  radicles  giving  rise  to  nitric  ethers),  it  illu- 
minates it  obliquely  from  another,  which  is  of  consid- 
erable importance  to  us.  In  all  aldehydes,  beginning 
with  the  formic  and  acetic,  a  tendency  to  polymeriza- 
tion is  to  be  noted,  due,  doubtless,  to  the  property 
of  aldehydes  of  entering  into  various  combinations 
(with  H3,  O,  NaHSO9,  etc.);  hence  the  composi- 
tion C6HlnO5,  containing  an  aldehyde  grouping, 
should  also  possess  this  property,  so  far  as  relates 
thereto.  We  may,  therefore,  safely  assume  that  the 
molecular  composition  of  cellulose,  judging  from  its 
properties,  is  polymerized,  i.e.,  it  is  of  the  form 
CeMH,owO6M,  where  n  is  probably  very  great.  If  we  as- 
sume n  =  5,  the  cellulose  becomes  of  composition 
C80H60OaB,  and,  for  the  highest  degree  of  nitration, 
CJOH36(NO2)1BOa§.  But  pyrocellulose  has  a  composi- 
tion C39H38(NOa),aO3B;  therefore,  the  number  of  inde- 
pendent nitro-celluloses  (nitric  ethers)  may  be  very 
large. 

This  is  very  important  in  the  conception  that  the 
nitration  of  cellulose  may  be  carried  up  to  any  desired 
degree,  and  for  known  concentrations  a  mixture  of 
nitric  and  sulphuric  acids  neither  dissolves  nor  reacts 
upon  a  product  of  nitration.  Again,  cellulose  is  the 
most  widely  disseminated  in  nature  of  all  the  hydro- 
carbons possessing  the  composition  C.H10OB,  consti- 
tuting the  tissues  of  all  plants  and  prepared  from  time 
immemorial  in  great  masses  as  cotton,  flax,  paper, 
etc.,  while  its  products  of  nitration  present  an  unal- 
terable material  suitable  for  conversion  into  smokeless 


120  SMOKELESS  POWDER 

powder.  This  side  of  the  matter  needs  no  further 
elucidation,  but  it  must  be  remembered  that  before 
the  development  of  pyrocollodion,  it  was  stated  that 
the  higher  the  nitration  of  the  cellulose  the  higher  the 
explosive  produced,  and  that  in  manufacturing  powder 
from  highly  explosive  nitro-cellulose  (of  composition 
about  C30H36[NOJUO25),  collodion(of  composition  about 
C30H40[NO3]10O8B)  was  added,  for  the  reason  that  higher 
nitro-celluloses  in  the  form  of  filaments  or  dust  were 
easily  detonated  (hence  their  employment  for  mines), 
while  the  Tatter  property  was  reduced  or  caused  to  dis- 
appear after  gelatinization,  of  which  collodion  was 
easily  susceptible  and  for  which  purpose  it  was  added. 
The  introduction  of  pyrocollodion  changed  existing 
views  upon  the  subject,  showing  that  maximum  force 
for  nitro-cellulose  was  not  to  be  sought  from  the  high- 
est degrees  of  nitration  (i.e.,  for  maximum  content  of 
nitrogen  and  oxygen),  but  that  it  obtained  for  that 
mean  degree  of  nitration  present  in  pyrocollodion. 
For  the  latter  material  F"1000  =  81.5  ;  while  for  nitro- 
cellulose of  maximum  nitration,  C8N7(NOa)sO6,  F1000  = 
74. 1 .  The  above  represents  only  one  side  of  the  theo- 
retical investigation  of  materials  suitable  for  smoke- 
less powder;  but  other  considerations  are  also  in  ac- 
cord, as  will  be  shown  later;  and  we  have,  therefore, 
gone  considerably  into  detail,  the  more  urgently  since 
it  has  been  necessary  to  struggle  with  prejudice, 
harmful  to  success  in  such  a  new  field  as  that  of 
smokeless  powders. 

Among  the  possible  materials  proposed,  apart  from 
mixtures  of  such  different  bodies  as  ammonium  nitrate 


PYROCOLLODION  SMOKELESS  POWDER        121 

and  various  organic  substances  (such  mixtures  were  re- 
jected in  practice),  must  be  considered  the  nitro-com- 
pounds  corresponding  to  benzol  and  its  derivatives, 
naphtalin,  etc.,  as  coal-tar  constitutes  an  abundant 
source  for  their  production  in  large  quantities,  and 
they  are  easily  nitrated.  From  the  class  of  the  so- 
called  "aromatic  compounds"  derived  from  benzol, 
C6H6,  it  is  useless  to  expect  smokeless  explosives  de- 
veloping large  volumes  of  F"1000,  although  many  are 
high  explosives,  beginning  with  Melinite  or  picric 
acid,  C6H9(NOa)8OH,  which  constitutes  a  powerful 
material,  although  far  from  the  best,  for  torpedoes 
and  explosive  shells;  and  since  some  of  the  first 
smokeless  powders  were  mixtures  containing  picric 
acid.  The  cause  of  the  small  gas  volumes  FIOOO  devel- 
oped by  the  aromatic  compounds  is  due  to  their  com- 
position, as  they  are  all  low  in  hydrogen.  This  view 
may  be  illustrated  by  a  few  examples. 

To  benzol  there  correspond  bodies  the  general  com- 
position of  which  may  be  expressed  by  the  formula 
CaH,_a(NOaV  If  a  equals  1,2  or  3  (these  substances 
are  known  and  easily  obtained),  the  oxygen  content  is 
insufficient  to  consume  the  carbon  into  CO  and  the 
hydrogen  into  H,O,  although  explosion  occurs  with 
the  formation  of  carbon  (smoke,  soot)  and  of  hydro- 
carbons. 

Total  smokelessness  could  be  realized  from  mixtures 
of  highly  nitrated  products,  as : 

4C.H3(NOa)4+  C.H4(NO,),  =  3oCO    +6H9O+9Na. 
Mol.  \vt.,  4X258+168  =  30X28  +  6X18+9X28=1200. 
Volume  of  gases  =  30X2    +6X2   +9X2  =90. 


122  SMOKELESS  POWDER 

If,  instead  of  such  non-existing  highly  nitrated  ben- 
zols, pyroxylin  be  employed  (as  in  the  American 
smokeless  powders  of  Munroe  and  other  inventors),  a 
gas  volume  approaching  that  developed  by  pyro- 
collodion  is  realized  : 


6C9H»NOa  +  26C«HTN9011  =  I92CO     +  io6HaO 
Mol.  wt.,  6  X  123  +  26  X  297  =  192  X  28  -f  106  X  18+42X28  =  8460. 
Volume  of  gases  =  193  X  2    -f  106  X  2  +42X2  =680. 
Fiooo  =  80.4. 

The  matter  assumes  a  different  aspect  if  ammonium 
nitrate,  NH4NO9,  be  employed  for  converting  the  car- 
bon and  hydrogen  of  nitro-benzol  into  CO  and  H3O. 
This  substance  contains  a  large  quantity  of  hydrogen  for 
a  relatively  small  content  of  oxygen  (but  for  this  re- 
sult a  large  quantity  of  NH4NO3  must  enter  into  the 
mixture),  and  greatly  increases  the  volume  of  gas 
developed,  as  is  evident  from  the  following  : 


2C,H.NOa  +  I3NH4N03       =  I2CO 
Mol.  wt.,  2  X  123  +  13  X  80  =  12  X  28  -f  3i  X  18  -f  14X28  =  1286. 
Volume  of  gases  —  12  X  2    +31X2    +14X2    =114. 


But  mixtures  of  this  salt  must  always  be  avoided  if 
a  satisfactory  smokeless  powder  is  to  be  produced,  as 
it  is  soluble  in  water,  as  well  as  hygroscopic,  and  pro- 
duces with  viscous,  oily  materials  only  coarse  mechan- 
ical mixtures. 

Similar  results  are  to  be  obtained  from  other  aro- 
matic substances,  and  we  may  refer  by  way  of  ex- 
ample to  mixtures  of  pyroxylin  with  picric  acid, 
C.H/NOO.OH,  and  nitro-naphtalin,  C10H7(NO3), 
such  compounds  having  been  recently  experimented 


PYROCOLLODION  SMOKELESS  POWDER         12$ 

with  (but  abandoned  in  practice)  as  smokeless  pow- 
ders. Among  other  disadvantages,  they  develop 
smaller  gas  volumes,  F]000,  than  pyrocollodion,  on 
account  of  their  relatively  small  content  of  hydrogen. 

After  an  examination  in  the  above  manner  of  the 
composition  and  properties  of  all  possible  materials 
capable  of  employment  as  smokeless  powders,  we 
arrive  at  the  following  deductions  in  relation  to  the 
volume  of  gases  (measured  at  given  temperature  and 
pressure),  F"1000,  developed  by  their  combustion: 

I. — Only  substances  containing  nitrogen,  carbon, 
hydrogen  and  oxygen  are  capable  of  entire  conversion, 
as  required  for  smokeless  powders,  into  gases  that  do 
not  react  upon  gun-metals.  Hence  all  other  explo- 
sive substances  (e.g.,  fulminate  of  mercury,  chloride  of 
nitrogen,  etc.)  containing  haloids,  metals,  phosphorus, 
etc.,  are  unsuitable  for  use  in  gunpowders. 

2. — When  the  combustion  of  carbon  results  in  the 
formation  of  carbonic  acid  gas,  COa,  a  less  volume  of 
gas  is  formed  than  when  carbonic  oxide,  CO,  is  the 
resultant  product ;  and  as  the  former  requires  more 
oxygen  than  the  latter,  the  increase  of  oxygen  or 
nitrogen  (if,  as  is  usually  the  case,  the  oxygen  enters 
into  combination  with  the  aid  of  the  elements  of  nitric 
acid)  is  injurious,  instead  of  useful,  although  there 
exists  full  conversion  into  gases  as  is  required  for 
smokeless  powder. 

3. — The  greater  the  quantity  of  hydrogen  in  the 
powder,  other  conditions  being  equal,  the  greater  the 
gas  volume,  F1000,  corresponding  to  the  combustion  of 
the  powder;  and,  therefore,  substances  derived  from 


124  SMOKELESS  POWDER 

the  limiting  (saturated)  series  of  hydrocarbons  are 
more  suitable  than  bodies  of  the  "aromatic"  series 
for  smokeless  powders. 

4. — Not  any  of  these  explosive  materials  not  contain- 
ing carbon  (as  NtH,  NH4NOa),  that  evolve  large  vol- 
umes of  gas  P1000  and  decompose  upon  ignition,  are 
such  as  will  not  detonate,  i.e.,  evolve  their  gases  so 
rapidly  that  they  crush  the  walls  of  guns ;  whence  it  is 
useless  to  consider  them  as  materials  adaptable  for 
conversion  into  smokeless  powders. 

5. — Some  of  the  materials  containing  but  little  car- 
bon and  much  hydrogen  may  prove  suitable  for  use  as 
powders  or  powder  mixtures,  evolving  large  volumes 
of  gas  upon  combustion ;  but,  so  far  as  known,  they 
are  either  volatile,  or  liable  to  decompose  spontaneously 
and  detonate,  or  else  they  are  prepared  with  difficulty 
from  mixtures  not  widely  disseminated,  so  that  at 
present  it  is  useless  to  look  for  materials  for  smokeless 
powder  from  among  them. 

6. — Nitro-glycerin  itself  develops  but  a  small  gas 
volume  (F1000  =  63.9),  as  it  contains  an  excess  of  oxy- 
gen. It  may  be  employed  in  mixtures  to  form  smoke- 
less powder,  and  its  mixtures  with  nitro-cellulose,  such 
as  Cordite  and  Ballistite,  which  are  practically  homo- 
geneous from  a  physical  standpoint,  develop  gas 
volumes,  F1IOO,  a  little  less  than  that  evolved  by  pyro- 
collodion  (although  such  mixtures  erode  guns,  as 
already  stated). 

7. — Cellulose,  C6MH10MOBW,  is  a  substance  widely  dis- 
seminated in  nature  and  of  general  industrial  employ- 
ment; by  its  non-volatility,  insolubility,  durability, 


PYROCOLLODION  SMOKELESS  POWDER         12$ 

etc.,  and  by  the  readiness  with  which  it  is  nitrated  (as 
it  contains  much  hydrogen),  it  constitutes  a  superior 
base  for  smokeless  powders. 

8. — Among  all  the  forms  of  nitro-cellulose  capable  of 
smokeless  combustion,  the  maximum  gas  volume,  F1000, 
corresponds  to  C30HS8NlaO49  (=  12.44  Per  cent,  nitro- 
gen), which  is  pyrocollodion,  for  which  F1000  =  81.5, 
and  which  is  capable  of  complete  gelatinization  in  a 
mixture  of  ether  and  alcohol,  in  which  form  it  is  com- 
pletely free  from  any  tendency  to  detonate.  In  the 
first  place,  it  is  the  most  suitable  of  all  the  nitro- 
celluloses;  in  the  second,  it  is  the  most  rational  and 
readily  obtainable  form  of  smokeless  powder,  destined 
to  supplant  not  only  other  smokeless  powders,  but  also 
to  replace,  by  reason  of  its  greater  homogeneity  and 
its  combination  of  qualities,  other  pyroxylin  powders. 

Pyroxylin  powder  is  a  mixture  of  nitro-celluloses, 
of  higher  nitration,  such  as  C6H,(NOa)3O6,  and  of  lower, 
as  CeH8(NO2)2O6;  pyrocollodion  is  a  definite  homo- 
geneous single  form  of  nitrocellulose.  By  changing 
the  proportional  relation  of  contents  of  the  high,  or 
insoluble,  and  low,  or  soluble,  nitro-cellulose,  it  is 
evidently  possible  to  make  the  pyroxylin  approach 
the  pyrocollodion  powders;  but  (as  has  been  shown 
in  recent  years,  especially  in  cannon-powders)  the  limit 
of  improvement  of  these  forms  always  falls  short  of 
pyrocollodion.  The  latter  is  homogeneous  and  un- 
changeable, while  pyroxylin  powders  vary  according 
to  their  composition.  However,  from  its  origin  it  is 
in  no  wise  different  from  the  perfected  powder  of 
Vieille  (although  considerably  different  from  the 


126  SMOKELESS  POWDER 

original  form  thereof),  presenting  instead  of  a  mix- 
ture, from  the  chemical  and  mechanical  standpoint, 
a  homogeneous  limiting  mass  of  the  composition 
C,0Hg8N12O49,  which  is  required  in  order  that  the  pow- 
der may  create  upon  combustion  the  maximum  volume 
of  vapor  and  gases.  It  is  certain  that  henceforth 
pyroxylin  powder  will  continue  to  approximate  to 
the  pyrocollodion  until  the  two  become  identical.  In 
brief,  pyrocollodion  represents  the  Russian  limit  of 
modification  and  improvement  of  the  French  pyroxy- 
lin powders,  the  development  of  which  marked  an 
epoch  in  ordnance  progress,  but  which  has  not  hitherto 
presented  an  invariable  and  constant  relation  of  the 
elements  entering  into  its  composition.  In  this  light 
pyrocollodion  powder  may  well  be  styled  Franco- 
Russian.  Begun  in  France,  it  has  been  completed  in 
Russia. 


APPENDIX  III 

THE   NITRATION   OF   COTTON 
By  M.  BRULEY 

WITHIN  recent  years  different  varieties  of  nitro- 
cellulose which  hitherto  have  possessed  only  very 
restricted  uses  have  had  their  fields  of  application 
broadened,  especially  in  their  relation  to  the  manu- 
facture of  explosives. 

Photographic  collodions,  celluloid,  artificial  silk, 
etc.,  have  nitro-cellulose  for  their  bases.  On  the 
other  hand,  besides  gun-cotton,  employed  for  military 
purposes,  as  for  the  charging  of  torpedoes  and  other 
similar  appliances,  nitro-cellulose  enters  into  the  com- 
position of  various  kinds  of  smokeless  powders,  gum- 
dynamites,  cartridges  for  use  in  presence  of  fire-damp, 
etc. 

Each  of  these  applications  demands,  so  to  speak,  a 
special  variety  of  nitro-cellulose,  and  the  government 
explosive-factories  entrusted  with  their  preparation, 
so  far  as  relates  to  their  use  as  explosives,  have  been 
gradually  forced  to  meet  requirements  differing  widely 
as  to  character. 

For  a  long  time  the  Moulin  Blanc  factory,  which 
was  established  for  the  production  of  naval  gun- 

127 


128  SMOKELESS  POWDER 

cotton,  had  scarcely  more  to  do  than  to  produce  gun- 
cotton  of  maximum  nitration  for  military  uses.  For 
this  the  well-known  mixture  of  three  parts  sulphuric 
acid  by  weight  of  65.5  Baume"  and  one  part  by  weight 
of  nitric  acid  of  48  Baume,  has  always  been  employed. 

Since  then  the  Moulin  Blanc  works  and  those  at 
Angouleme,  where  the  manufacture  of  gun-cotton  was 
established  in  1887,  have  had  to  produce  other  kinds 
of  nitro-cellulose,  which  it  became  necessary  to  man- 
ufacture practically  in  a  regular  manner. 

The  theoretical  researches  of  M.  Vieille,  described 
in  his  note  of  September  13,  1883,  inserted  in  Vol.  II 
of  the  "  Memorial  des  Poudres  et  Salpetres  "  (p.  212 
et  seq.),  classified  different  varieties  of  nitro-cellulose 
in  the  manner  following,  in  accordance  with  the 
formulae  for  their  chemical  composition : 

Vol.  of  Nitrogen  Dioxide 
Disengaged  per  gram 

Cellulose  endecanitrate 214  ) 

v  gun-cottons, 
decamtrate 203  ) 

"  enneanitrate 190  \ 

"  octonitrate 178  >•  collodions. 

"  heptanitrate 162  ) 

"  hexanitrate 146  \ 

l<  pentanitrate 128  V  friable  cottons. 

"  tetranitrate 108  ) 

Gun-cotton,  as  well  as  friable  cottons,  are  insoluble 
in  a  mixture  of  alcohol  and  sulphuric  ether,  while 
collodions,  on  the  contrary,  are  soluble  in  such  a 
mixture. 

Indeed,  it  is  hardly  possible  to  isolate  each  one  of 


THE  NITRATION   OF  COTTON 

these  varieties,  and  one  always  finds  mixtures  of  two 
or  more  neighboring  varieties. 

Thus  in  practice,  the  products  obtained  are  classed, 
not  into  cellulose  endecanitrate,  cellulose  decanitrate, 
etc.,  but  into  gun-cotton  properly  so-called,  for  which 
the  content  of  nitrogen  is  between  210  and  200  c.c., 
into  superior  and  inferior  collodions,  with  nitrogen 
content  ranging  between  190  and  1 80  c.c.  'for  the 
former  and  from  180  to  170  for  the  latter;  .and  friable 
cottons. 

Gun-cotton,  properly  so-called,  is  theoretically  in- 
soluble in  ether-alcohol.  In  reality  it  always  contains 
small  quantities  of  less  highly  nitrated  soluble  products. 
Collodions  deposit  in  this  solvent  an  insoluble  residue, 
due  to  the  presence  of  non-attacked  cotton,  or  friable 
cottons,  or  even  more  highly  nitrated  cottons. 

It  is  for  this  reason-  that  solubility  in  ether-alcohol 
is  determined  the  same  time  that  nitration  is  estimated. 

The  different  soluble  collodions  are  distinguishable 
from  one  another,  moreover,  by  the  greater  or  less 
viscosity  of  the  solution  obtained.  As  this  property 
is  one  that  may  possess  practical  importance  in  the 
employment  of  collodions,  it  appears  useful  to  study 
it  simultaneously  with  the  solubility  and  the  content 
of  nitrogen. 

A  series  of  researches  were  undertaken  at  the  An- 
gouleme  powder- works  for  the  purpose  of  determining 
the  practical  method  of  obtaining  a  chosen  product 
from  the  series  of  those  just  enumerated.  These 
researches  do  not  claim  to  possess  the  scientific  value 
of  those  made  in  1883  by  M.  Vieille  upon  the  nitra- 


130  SMOKELESS  POWDER 

tion  of  cotton.  The  resources  at  the  powder-works 
laboratory,  especially  in  relation  to  personnel,  are  too 
limited  to  justify  the  hope  of  rigorous  precision  for 
results  obtained.  But  apart  from  their  utility  as  a 
guide  in  the  manufacture  of  a  desired  product,  they 
seem  to  possess  a  certain  interest  in  relation  to  the 
conditions  controlling  the  nitration  of  cotton. 

I.    METHOD     OF    NITRATION     AND     MODE    OF    REPRE- 
SENTING  RESULTS 

M.  Vieille  in  his  researches  in  1883  had  employed 
two  methods  of  nitration.  In  one  he  used  mixtures 
containing  only  nitric  acid  and  water.  In  the  other 
he  added  to  these  bodies  variable  proportions  of  sul- 
phuric acid. 

The  latter  method  has  been  alone  employed  in 
practice;  it  is  the  one  exclusively  used  in  the  trials 
that  constitute  the  object  of  the  present  work. 

Apart  from  nitrous  vapors,  which  are  always  present 
in  appreciable  but  very  feeble  quantities,  and  foreign 
matters,  which  are  never  found  in  the  acids  employed 
except  in  negligable  quantities,  every  mixture  em- 
ployed for  dipping  cotton  for  the  production  of  any 
one  of  the  various  nitro-celluloses  contains  the  three 
following  elements:  monohydrated  sulphuric  acid, 
H3SO4;  monohydrated  nitric  acid,  HNO3;  and  water, 

H,O. 

If  we  desire  to  classify  the  infinite  number  of  mix- 
tures that  may  be  obtained  from  all  possible  combin- 
ations of  the  three  elements,  in  groups  giving  rise 


THE  NITRATION  OF  COTTON  \$l 

finally  to  products  of  the  same  kind,  it  is  necessary  to 
have  recourse  to  a  graphic  method  of  representation  of 
these  mixtures. 

In  expressing  the  relations  of  the  proportions  of 
the  two  elements  to  the  third,  each  mixture  is  de- 
fined by  only  two  numbers.  It  is  easy,  then,  by  em- 
ploying one  of  them  as  an  abscissa  and  the  other  as 
an  ordinate,  to  express  by  the  ordinary  system  of 
rectangular  coordinates  any  mixture  determined  by  a 
single  point. 

The  different  mixtures  giving  rise  to  the  same 
product  will  thus  be  grouped  by  zones,  and  a  knowl- 
edge of  these  zones  will  facilitate  the  practical  obtain- 
ing of  a  desired  nitro-cellulose,  whether  new  acids  are 
employed  to  produce  it  or  whether  spent  acids  from  a 
previous  manufacture  are  employed  for  the  purpose. 

II.    RESULTS   OBTAINED    BY    M.    VIEILLE 

We  shall  reconsider,  in  the  order  of  ideas  just  in- 
dicated, the  results  obtained  by  M.  Vieille  in  1883, 
and  mentioned  in  the  preceding  note. 

In  all  experiments  under  the  second  method,  sul- 
phuric acid  of  density  1.832  was  employed,  corre- 
sponding, according  to  the  special  tables,  to  a  degree 
by  areometer  of  65.5  Baum£  and  to  a  percentage  of 
water  of  about  8  ;  and,  upon  the  other  hand,  to  nitric 
acid  of  density  1.316  which,  if  it  be  supposed  free  from 
all  traces  of.  nitrous  vapors,  should  mark  34.6  by  the 
Baume  areometer  and  contain  50$  of  water. 

Applying  these  figures  to  the  volumetric  proper- 


132 


SMOKELESS  POWDER 


tions  of  each  mixture  given  in  the  table  on   page  87, 
the  following  new  table  is  formed : 


No.  of  Ex- 
periment 

Proportions  of  Components 

Per  cent,  of  Ni- 
trogen Dioxidein 
Product  ob- 
tained 

Observations 

H5S04 

HN03 

HaO 

I 

100 

13.1 

21.7 

195-9 

2 

100 

15-5 

24-3 

190.1 

3 

100 

19-5 

28.2 

184.6 

4 

100 

22.9 

31.7 

185.5 

5 

100 

26.0 

34-8 

182.3 

Solubility 

6 

IOO 

27.8 

36.5 

164.0 

not    deter- 

7 

100 

30.0 

38.6 

166.7 

mined 

8 

IOO 

32.4 

41.1 

166.0 

9 

IOO 

35.4 

44-1 

I4I.2 

10 

IOO 

39-o 

47.6 

143.5 

ii 

IOO 

41.0 

49.8 

133-2 

12 

IOO 

43.3 

61.9 

132.7 

Under  the  system  of  representation  adopted,  by 
which  the  proportions  of  the  two  other  elements  are 
expressed  as  ratios  to  100  parts  by  weight  of  H,SO4, 
the  figures  of  the  preceding  table  may  be  graphically 
expressed  as  in  Fig.  i,  page  133. 

All  the  points  representing  the  mixtures  employed 
lie  upon  the  same  straight  line  ab,  since  they  are 
formed  with  the  same  nitric  acid  marking  34.6°  by  the 
Baume"  areometer.  This  line  is  inclined  at  45°,  since 
the  acid  chosen  contains  as  much  water  as  mono- 
hydrated  acid;  it  starts  from  the  point  a  correspond- 
ing to  eight  per  cent.,  there  being  exactly  that  much 
water  in  one  hundred  parts  of  the  sulphuric  acid  to 
which  the  one  hundred  parts  of  the  other  components 
are  expressed  as  ratios. 

Outside  of  this  line  there  exist  an  infinite  number  of 
other  points  corresponding  to  acid  mixtures  the  action 


THE  NITRATION  OF  COTTON  133 

of  which  upon  cotton  was  not  studied  by  M.  Vieille. 
By  employing  nitric  acid  of  increasing  strengths  succes- 
sively, along  with  sulphuric  acid  of  65.5°  Baume",  mix- 
tures will  be  obtained  represented  by  points  upon 
the  lines  ac,  ad,  etc.,  which  start  from  the  common 
point  a  and  are  more  or  less  inclined  according  to  the 


Q 
§ 

o  45- 


Q 

§20- 
o 


* 

u. 

o 
giOH 


5     Ct  i'o        15         20        25        3b        &        40         45        SO 

PROPORTION  OF  WATER  TO  100  PARTS  OF  SULPHURIC  ACID. 

FIG.  i 

quantity  of  water  in  the  acid  employed.  The  practical 
limit  is  the  line  af  corresponding  to  48°  Baume",  the 
strongest  obtainable  in  current  manufacture,  and  which 
contains  about  10  per  cent,  water. 

These  are  the  regions  left  aside  in  previous  studies, 
the  exploration  of  which  is  now  undertaken  from  the 


134  SMOKELESS   POWDER 

standpoint  of  practical  results  to  be  obtained  industri- 
ally from  the  corresponding  acid  mixtures. 

III.     EXPERIMENTS    IN    NITRATION.        (FIRST    SERIES) 

In  this  first  series  of  experiments  the  base  material 
was  the  chemically  pure  absorbent  cotton  employed  in 
pharmacy.  ~  The  acid  mixtures  were  prepared  direct 
from  the  three  principal  elements,  sulphuric  acid,  nitric 
acid  and  water.  For  this  purpose  a  carboy  of  sul- 
phuric acid  of  65.7°  Baum6  was  drawn  from  current 
supplies.  On  the  other  hand  a  certain  quantity 
of  nitric  acid  of  the  highest  possible  strength  had 
been  collected  at  the  nitric-acid  factory,  and  from  this 
nitrous  vapors  were  completely  expelled  by  passing 
carbonic-acid  gas  through  it  for  a  number  of  hours  at 
a  temperature  of  about  70°  C.  After  expulsion  of 
fumes  this  acid  marked  47.7°  Baume. 

The  selected  sulphuric  and  nitric  acids  were  kept  in 
carboys  carefully  sealed  and  provided  with  a  com- 
pressed-air emptying  system,  the  air  used  being  care- 
fully freed  from  all  traces  of  moisture.  As  all  the  ex- 
periments could  not  be  carried  on  at  the  same  time,  it 
was  necessary  to  provide  that  the  elements  entering 
into  them  should  be  always  identical. 

The  water  present  in  the  acids  was  that  shown  by 
the  special  table  corresponding  to  their  areometric  de- 
gree, this  quantity  being  checked  by  direct  analysis, 
and  was  6.5  per  cent,  for  the  sulphuric  and  10.5  per 
cent,  for  the  nitric  acid. 

The  mixtures  employed  for  the  experiments  were 
determined  by  adding  to  the  quantities  of  the  two 


THE  NITRATION  OF  COTTON  135 

acids  taken  the  quantity  of  water  necessary  to  bring 
the  total  weight  up  to  1.2  kilos.  The  percentage 
compositions  were  deduced  from  these  weights  and 
that  of  the  water  in  the  acid  components. 

Each  mixture  was  divided  into  three  lots  of  400 
grams  each,  of  which  two  were  employed  for  dupli- 
cate experiments  and  one  was  held  in  reserve. 

The  400  grams  of  mixed  acid  were  introduced  into  a 
large-mouthed  flask  provided  with  an  air-tight  stopper, 
and  an  equilibrium  of  temperature  established ;  then 
the  four  grams  of  absorbent  cotton  were  added  and 
the  flask  violently  shaken.  Under  these  conditions 
nitration  took  place  almost  instantaneously,  and  it 
may  be  said  that  each  fibre  of  cotton  was  instantly 
surrounded  with  100  times  its  weight  of  liquid  acid. 

The  flask  was  then  corked  and  placed  under  a 
stream  of  water  maintained  at  a  constant  temperature 
of  from  1 8°  to  19°  C.,  which  was  that  of  dipping,  the 
cotton  remaining  the  whole  time  in  the  acid  bath. 

Two  dippings  were  made  for  each  mixture  studied, 
one  of  them  corresponding  to  reaction  double  in  length 
of  time  to  that  of  the  other.  The  admitted  durations 
of  reaction  were  six,  twelve,  and  twenty-four  hours, 
according  to  the  kind  of  nitro-cellulose  that  was  sup- 
posed should  be  obtained. 

It  was  not  considered  necessary  to  study  reactions 
of  longer  duration,  difficult  to  realize  in  practice.  In 
certain  cases  it  was  deemed  sufficient  to  control  results 
by  reconducting  the  experiment  in  a  bath  of  the  same 
composition,  and  allowing  the  reaction  to  continue 
for  forty-eight  and  even  up  to  sixty  hours. 


136  SMOKELESS  POWDER 

Twenty-five  mixtures,  corresponding  pretty  nearly 
to  the  whole  region  embraced  by  those  obtainable  in 
practice,  were  thus  experimented  with ;  that  is  to  say, 
by  maintaining  as  proportions  of  nitric  acid  and  water 
expressed  in  ratios  to  one  hundred  parts  of  sulphuric 
acid  by  weight,  from  10  to  60  per  cent,  of  the  former 
and  from  10  to  45  per  cent,  of  the  latter. 

In  fact,  for  nitric  acid  below  a  certain  limit,  reac- 
tions became  too  slow.  On  the  other  hand,  from  a 
standpoint  of  economy,  its  proportion  cannot  be  too 
much  increased  on  account  of  its  relatively  high  price. 
As  to  water,  its  lower  limit  is  fixed  by  the  strength 
of  the  strongest  acids  obtainable  in  current  manufac- 
ture. 

The  twenty-five  mixtures  studied  represent  suffi- 
ciently well,  then,  the  region  that  may  be  explored  in 
practice ;  they  are  spaced  apart  regularly,  so  that  by 
the  examination  of  the  products  obtained,  proper  ac- 
count may  be  taken  of  the  phenomenon  of  nitration 
throughout  the  region  explored. 

The  percentage  of  nitrogen  in  each  of  the  products 
thus  obtained  was  determined  by  Schloessing's  method, 
described  at  the  close  of  M.  Vieille's  paper  above  re- 
ferred to.  Solubility  in  ether-alcohol  and  viscosity  in 
that  medium  were  determined  under  the  methods  em- 
ployed at  the  Angouleme  powder- works  and  described 
at  the  end  of  the  present  paper. 

The  following  table  presents  a  resume  of  all  results 
obtained  from  the  analysis  of  specimens  produced  in 
this  first  series  of  experiments : 


THE  NITRATION  OF  COTTON 


137 


I" 

a 

2 

,     ^ 

M     ^>d     MCO                                                                                                                                in            t-            ^ 

0 

If* 

d     M     TfrO     ^t"                                                                                                                               M              d             lO 
M    ON 

0 

N 

o 

O  NO    d  CO    d                                                                                                             CO          CO          00 

eaction 

g    * 

MMQoor^                                                                            MOO 

ation  of  F 

I 

M                    T}-O  comm        Od\o        co         M         ^- 

3 

Q 

G 

=!>•<* 

in         MTf-WMvO         ^OOOONONOcodxnvONOxnO^MO 

4 

u 
O 

0 

E 

Sl-s 

•a 
V 
c 

c      fi 

COOOd'-l-COd           CO^dOdTtvOdCOCOvOOONOCOCOCO 

rt 

§sd«- 

S^^^g^^^g:     ^  o^^w^R^o^o  ^oco"2  0^0°  o" 

0 

g   ^ 

1 

D 

Pi 

i" 

co  r^  M  co  M         Tfo  O       O         co       m 
d  vo  co    ^*O         d  in  co         M         d         in 

M                                                 M     d                      M              M 

. 

JK 

m                            1^        CMnO   0.0  -oo  IO*M  n»       »        oo 

3 

O 

E 

NO 

'5-5  ° 

S                 R     S^^gRSS*^    S    8 

«1  "„• 

O                                   d         vO    rf  ^co    ^  't'vO  vO    ^  T}-  O    Tj-        vO          ^ 

IS,«.S 

S"                                  0^         0    ON^CO    Ro'^^S    ^Oc?         0^        1C 

M) 

O  coco  d  co  d   ^t  d   ONCO  mM   d   rt-d   Ttr>ii-(in>-io   ONM   ot^ 

3 

rt 

O>  ^CO    Tf  rf  ^-  CO  Tf  CO   ONCO    T   ^tCO    CO   rj-   ON  ON  *f  *f  O*CO    ON  0s  OO 

t 

•Ss 

MMvOrM-^Mu,coOONdcoONt-comdOcocoinO^ON 

G 

11 

ONONONONONONONONON  O^CO     ON  &    ON  ONCO  CO  CO    O>  CO     ON  ON  ON  ON  Tf 

•3 

I 

*3  3'D 

§^      -      M 

u 

t 
| 

L| 

"o     S 

^                             Jx^^N         rik^£>^S         ^S/*^^^ 

138  SMOKELESS  POWDER 

Inspection  of  this  table  shows  that  mixtures  in 
which  the  percentage  of  nitric  acid  is  low,  and  no- 
tably mixtures  V  and  VI,  produce  after  twelve  hours 
reaction  an  incompletely  nitrated  product.  Even 
after  twenty-four  hours  the  nitration  is  not  com- 
plete; a  fact  verified  by  certain  complementary  ex- 
periments for  these  latter.  They  will  be  discarded, 
then,  as  out  of  the  category  of  practical  mixtures. 

The  graphic  representation  of  the  other  mixtures, 
by  the  method  above  indicated,  is  reproduced  below 
(Fig.  2).  By  the  side  of  each  point  representing  one  of 
them,  the  corresponding  number  is  indicated  in  Ro- 
man numerals;  and  the  principal  qualities  of  the  prod- 
uct taken  from  the  preceding  table  are  expressed  in 
ordinary  figures,  the  figures  chosen  for  each  reaction 
being  those  corresponding  to  the  longest  duration  of 
reaction.  The  first  number  is  the  percentage  of  ni- 
trogen; the  second,  the  solubility;  the  third,  when 
given,  the  viscosity. 

If,  as  indicated  at  the  beginning  of  this  article,  the 
products  be  divided  into  gun-cottons,  collodions  and 
friable  cottons,  overlooking  certain  small  quantities 
of  accompanying  products  that  may  be  mingled  with 
them,  it  will  be  seen  that  mixtures  giving  rise  to 
products  of  the  same  kind  may  be  grouped  in  quite 
distinct  zones.  The  lines  which  limit  these  zones  are 
nearly  parallel  to  one  another.  They  depart  a  little 
from  the  straight  line  and  are  slightly  inclined  to  the 
co-ordinate  axes;  percentages  of  nitrogen  and  solu- 
bilities alone  have  served  for  tracing  them.  Vis- 
cosities, which  refer  to  collodions  only,  are  pre- 


THE  NITRATION   OF  COTTON 


139 


sented  only  as  indicators,  and  are  far  from  being  the 
same  for  all  products  in  a  given  zone. 


cr 

Q. 
8 

O  U 
I-H 


5=:i 

cr  Q. 
I-  -J 


g     15- 

o: 

§     10- 
cc 

Q. 


0  5  10          15          20          25          30          35          40          45 

PROPORTION  OF  WATER  TO  100  PARTS  OF  SULPHURIC  ACID  (MONOHYDRATE) 
FIG.  2 

Without  being  able  to  discover,  in  results  obtained 
for  these  viscosities,  the  expression  of  any  well-de- 
fined law,  it  may  be  remarked,  however,  that  they  are 


140  SMOKELESS  POWDER 

in  general  greater,  according  as  the  corresponding 
percentages  of  nitrogen  themselves  are  greater.  Thus 
it  is  to  be  remarked  that  the  mean  viscosity  for  the 
zone  of  lower  collodions  is  65%  while  for  the  higher 
collodions  the  mean  attains  I4OS. 


IV.    EXPERIMENTS    IN    NITRATION.       (SECOND    SERIES) 

The  preceding  results  were  obtained,  as  indicated, 
with  pure  wadded  cotton.  In  general  this  is  not  the 
base  material  employed,  but  spinning  waste,  bleached 
and  freed  from  grease,  which  costs  less.  The  fibres 
of  the  cotton  are  more  or  less  twisted  and  entangled, 
and,  notwithstanding  the  effects  of  carding,  there 
always  remain  at  the  time  of  dipping  small  agglom- 
erations, into  which  the  acid  penetrates  with  diffi- 
culty. In  order  to  estimate  the  influence  of  the  base 
material  employed  upon  results  obtained,  a  second 
series  of  trials  were  undertaken  under  conditions 
similar  to  those  of  the  first  series,  except  that  the 
refuse  cotton  from  current  manufacture  was  substi- 
tuted for  the  absorbent  wadding.  During  this  series 
of  experiments  the  temperature  was  maintained  dur- 
ing the  whole  time  of  the  dipping  at  about  from  7°  to 
8°  C.  The  acid  mixtures  were  prepared  as  indicated 
above.  The  sulphuric  acid  employed  marked  65.8° 
Baume,  and  contained  only  5  per  cent,  of  water. 
The  nitric  acid,  freed  from  nitrous  vapors,  marked 
47.  i  °  Baume  and  contained  1 5  per  cent,  of  water.  The 
per  cent,  composition  of  each  of  the  twenty-five  mix- 


THE   NITRATION  OF  COTTON  14* 

tures  employed  was  calculated  on  the  basis  of  these 
figures,  and  verified  for  a  certain  number  of  cases  by 
direct  analysis.  As  above  stated,  4  grams  of  cotton 
were  immersed  in  400  grams  of  acid.  The  absorp- 
tion of  the  cotton  by  the  liquid  proceeded  as  rapidly 
as  with  the  wadding. 

The  table  on  page  142  presents  the  results  ob- 
tained in  the  second  series  of  experiments. 

More  clearly  than  in  the  preceding  series,  it  is  to 
be  remarked  that  for  a  certain  number  of  mixtures, 
especially  for  those  in  which  the  relative  proportion 
of  nitric  acid  is  low,  prolongation  of  the  reaction  in- 
creases the  percentage  of  nitration.  We  shall  dis- 
card mixtures  V  and  VI  as  heretofore,  since  the  re- 
action, to  be  complete,  would  have  to  be  prolonged 
too  far. 

Figure  3  (page  143)  represents  graphically  the 
results  of  the  second  series  of  experiments. 

As  in  the  preceding  series,  different  mixtures,  pro- 
ducing products  of  the  same  kind  are  grouped  in 
zones,  and  these  zones  are  sensibly  of  the  same  form 
as  those  of  Fig.  2;  still  again,  but  this  time  perhaps 
a  little  less  clearly,  however,  the  viscosity  of  the  col- 
lodions appears  to  increase  with  the  percentage  of 
nitration. 

V.    EXPERIMENTS  IN  NITRATION.       (THIRD  SERIES) 

A  third  series  of  dippings  was  finally  undertaken, 
the  conditions  of  which  were  practically  identical 
with  those  obtaining  in  practice.  Bleached  English 


142 


SMOKELESS  POWDER 


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THE  NITRATION1  OF  COTTON 


143 


spun-cotton  waste  from  the  powder-factory  supplies, 
was  employed  as  the  base  material.  This  was  dipped 
in  different  acid  mixtures  formed,  as  indicated  above, 


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PROPORTION  OF  WATER  TO  100  PARTS  OF  SULPHURIC  ACID  (MONOHYDRATE) 

FIG.    3 

from  distilled  water  and  the  sulphuric  and  nitric  acids 
of  which  part  had  been  employed  in  the  preceding 
experiments.  The  proportions  for  dippings  were  al- 


144  SMOKELESS  POWDER 

ways  the  same;  4  grams  of  cotton  to  400  grams  of 
mixed  acids;  but  the  duration  of  immersion  of  the 
cotton  in  the  acid  bath  was  reduced  to  eight  minutes. 
After  such  immersion  at  a  constant  temperature  (12° 
to  13°  C.  approx.)  the  cotton  was  removed,  drained, 
lightly  pressed,  and  placed  in  an  earthenware  crock 
in  which  the  reaction  completed  itself,  the  pot  being 
placed  in  a  stream  of  water  at  the  current  tempera- 
ture. 

The  results  from  this  third  series  of  experiments 
are  given  in  the  table  on  page  145. 

These  results  may  be  expressed  graphically  in  the 
manner  shown  in  Fig.  4,  page  146,  neglecting  mix- 
tures V,  VI  and  XXV,  which  only  produced  partially 
nitrated  products. 

Still  again,  the  products  obtained  allow  the  mix- 
tures to  be  grouped  into  zones  analogous  to  those 
resulting  from  the  two  other  series  of  experiments. 
In  each  of  these  zones  viscosities  are  variable  and  ap- 
pear not  to  follow  a  well-defined  law,  although  high 
viscosities  accompany  the  highest  percentages  of 
nitrogen. 

VI.    VARIOUS    EXPERIMENTS 

The  experiments  of  which  a  resume  has  just  been 
given  exhibit  the  influence  of  acid  mixtures  upon  the 
products  obtained.  Here,  indeed,  lies  the  principal 
element  entering  into  the  whole  manufacture  of  nitro- 
cellulose. But  other,  secondary  causes  may  equally 
influence  final  results,  and  it  has  appeared  useful  to 


NITRATION'  OF  COTTON' 


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146 


SMOKELESS  POWDER 


study  them  also.  Among  these  causes,  duration  of 
reaction  has  been  briefly  touched  upon  already,  as 
well  as  the  nature  of  the  base  material.  To  these  must 


v  5  10          1J5          20         ~3T        30          35          40          45 

^  PROPORTION  OF  WATER  TO  100  PARTS  OF  SULPHURIC  ACID. 

FIG.  4 

be  added  temperature  during  dipping  and  reaction,  as 
well  as  the  later  effect  of  the  manipulations  that  ni- 
trated cotton  may  undergo  after  the  operation  of 


THE  NITRATION  OF  COTTON  147 

dipping.  These  different  effects  will  be  examined 
successively. 

Base  materials. — Cotton  wadding  nitrates  more 
readily  than  spun-cotton  waste,  which  nitrates  with 
the  greater  difficulty  the  more  it  is  tangled,  the 
coarser  its  threads,  and  the  more  knots  it  con- 
tains. On  the  other  hand,  it  equally  appears  that  the 
previous  preparation  of  the  waste  destined  for  dip- 
ping exercises  a  very  sensible  influence  upon  the  vis- 
cosity of  the  collodions  obtained.  Thus  it  is  that  two 
cottons  of  absolutely  different  origin,  submitted  un- 
der identical  conditions  to  the  action  of  a  common 
acid  mixture,  produce  collodions  possessing  the  same 
mean  percentage  of  nitrogen,  but  with  viscosities 
varying  from  what  they  ordinarily  are  to  double  this. 

Duration  of  reaction. — The  appended  table,  in 
which  two  or  three  durations  of  reaction  correspond 
to  each  mixture,  shows  that  for  a  same  final  product, 
the  reaction  should  be  the  more  prolonged  the  lower 
the  proportion  of  nitric  acid  in  the  mixture. 

Some  experiments  were  made  to  follow  more 
closely  the  progress  of  the  reaction;  a  resume  of  them 
is  presented  in  the  following  table.  These  experi- 
ments refer  to  three  acid  mixtures  from  the  first 
series,  the  numbers  of  which  are  recalled  in  reference 
to  results  obtained;  the  conditions  of  dipping  and  re- 
action are  those  of  this  series;  the  temperature  of 
the  reaction  was  about  20°  C.  approximately : 


148 


SMOKELESS  POWDER 


Mixtur 

2  XIII 

Mixtur 

eXVI 

Mixtur 

eXXI 

T^ 

of 
Reaction 

Nitrogen 
c.c.  NOa 

Solubility 
in* 

Nitrogen 
c.c.  N0a 

Solubility 
\n% 

Nitrogen 
c.c.  NO2 

Solubility 
in% 

I   hour 

165.8 

91.7 

186.8 

94.9 

206.4 

10.9 

2  hours 

166.8 

95-5 

189 

95-0 

209.4 

8-3 

4 

167.8 

93-0 

191.8 

96.2 

209.2 

6.8 

6 

167.8 

94-8 

198 

94.1 

2IO.2 

6-7 

8 

166.8 

95-4 

191.8 

96.7 

2IO.2 

5-6 

12 

210.8 

7-4 

24 

166.8 

98.1 

194 

96.6 

210.6 

10.6 

These  experiments  comprise  the  three  principal 
types  of  nitro-cellulose  studied;  superior  and  inferior 
collodions  and  gun-cotton.  They  show  that  for  the 
two  former  a  maximum  of  nitration  is  hardly  ob- 
tained before  the  end  of  two  hours  of  reaction;  for 
gun-cotton,  on  the  other  hand,  from  eight  to  ten 
hours  are  required.  If  the  reaction  be  prolonged 
beyond  these  limits,  the  solubility  has  a  tendency  to 
increase.  In  these  experiments  viscosity  could  not 
be  measured;  but  the  preceding  tables  seem  to  show 
that  no  relation  exists  between  it  and  duration  of  re- 
action. 

Temperatures  of  dipping  and  reaction. — A  certain 
number  of  dippings  were  made  under  conditions  iden- 
tical with  those  of  the  second  series  of  experiments, 
at  the  three  very  different  temperatures  of  i°,  12° 
and  25°  C.  These  temperatures  were  maintained 
throughout  the  whole  duration  of  the  reaction. 

Results  obtained  are  grouped  in  the  following 
table: 


THE  NITRATION   OF  COTTON 


149 


Temperature  during  Dipping  and  Reaction 

•g 

°z 

Is 

11 

i°C. 

12°  C. 

25"  C. 

•~   3 

u  w 

1* 

hrs. 

Nitro- 
gen as 
NO, 
in  c.c. 

Solu- 
bility 
in* 

Vis- 
cos- 
ity 
s. 

Nitro- 
gen as 
NO, 
in  c.c. 

Solu- 
bility, 
in* 

Vis- 
cos- 
ity 
s. 

Nitro- 
gen as 
NO, 
in  c.c. 

Solu- 
bility 
in  * 

Vis- 
cos- 
ity 
s. 

I 

6 

190.0 

95-9 

180 

191.8 

97.8 

104 

193.2 

97-7 

56 

III 

12 

208.2 

1-5 

207.4 

1-7 

207.8 

I.O 

VI 

12 

2OI.6 

4.4 

205.4 

4.4 

207-6 

3-6 

VII 

6 

177.6 

84-9 

22 

189.0 

92.9 

60 

193.2 

97-7 

36 

X 

6 

178.8 

95-1 

145 

185.4 

96.8 

72 

184.4 

96.2 

61 

XII 

6 

167.2 

78.9 

38 

172.0 

92.9 

36 

172.0 

96.1 

27 

Other  experiments  were  made  to  the  same  end 
with  wadded  cotton  under  the  conditions  of  the  first 
series.  The  results  were  as  follows: 


Temperature  during  Dipping  and  Reaction 

"8 

•o 

c  - 

3s 

•2-2 

ti  o 

,    2°C. 

15°  C. 

26°  C. 

VM   3 
°« 

& 

JJ 

hrs. 

Nitro- 
gen 
NO, 
in  c.c. 

Solu- 
bility 
in* 

Vis- 
cos- 
ity 
s. 

Nitro- 
gen 
NO, 
in  c.c. 

Solu- 
bility 
in* 

Vis- 
cos- 
ity 
s. 

Nitro- 
gen. 
NO, 
in  c.c. 

Solu- 
bility 
in* 

Vis- 
cos- 
ity 
s. 

XII 

6 

183.2 

96.5 

186.8 

96.7 

189.2 

97.3 

" 

12 

183.2 

97-4 

186.8 

95-1 

188.2 

94-4 

XIII 

6 

167.4 

93-8 

169.0 

93-2 

1 

173-4 

93-0 

11 

12 

165.6 

90.7 

166.0 

94-5 

168.6 

94.1 

XV 

6 

188.8 

96.5 

43 

192.8 

98.1 

48 

194.0 

93.3 

22 

«• 

12 

188.8 

97-4 

37 

191.8 

97.0 

26 

193.6 

98.1 

20 

XXI 

12 

208.8 

8.9 

209.2 

9.2 

208.6 

7-i 

24 

209.8 

6.7 

209.2 

7.0 

208.4 

8.4 

These  experiments  seemed  to  show  that,  so  far  as 
collodions  were  concerned,  increase  of  temperature 
during  dipping  and  reaction  increases  the  percentage 
of  nitrogen  and  the  solubility,  but  sensibly  diminishes 


I $O  SMOKELESS  POWDER 

the  viscosity.  In  other  words,  a  low  temperature  re- 
tards the  reaction.  In  what  relates  to  gun-cottons, 
the  influence  manifests  itself  less  distinctly;  it  is  ad- 
mitted, however,  that  at  high  temperatures  the  solu- 
bility has  a  tendency  to  increase. 

Subsequent  manipulations. — The  different  cellu- 
loses are  submitted  before  use  to  a  number  of 
manipulations;  first  to  washings,  which  are  necessary 
to  remove  the  last  traces  of  acidity,  and  for  certain 
ones  to  pulping,  which  serves  to  facilitate  subsequent 
operations. 

Washing  is  effected  by  a  more  or  less  prolonged 
boiling,  either  in  pure  water  or  in  an  alkaline  solu- 
tion; the  pulping  by  beating-engines  similar  to  the  ap- 
paratus employed  in  the  manufacture  of  paper. 

These  operations,  which  are  absolutely  mechanical, 
have  no  influence  upon  the  chemical  composition  of 
the  final  product,  and  therefore  upon  the  percentage 
of  nitrogen;  but  it  is  different  for  solubility  and  vis- 
cosity, which  are  purely  physical  properties. 

Experiments  were  made  with  the  view  of  ascertain- 
ing how  various  kinds  of  nitro-celluloses  acted  during 
these  operations.  Results  are  grouped  in  the  tables 
on  page  151. 

These  various  experiments  were  made  with  quite 
large  quantities  of  gun-cotton,  consequently  more  or 
less  homogeneous,  so  that  taking  of  samples  should 
suffice  to  explain  certain  anomalies  to  be  noticed  in 
the  progress  of  phenomena  observed.  From  the 
figures  in  the  preceding  tables  it  may  be  concluded, 
on  the  one  hand,  that  the  two  operations  of  washing 


THE   NITRATION  OF  COTTON 


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I $2  SMOKELESS  POWDER 

in  warm  water  and  pulping  have  the  effect  of  increas- 
ing the  solubility  of  gun-cottoils;  on  the  other  hand, 
that  these  two  operations  diminish  to  a  marked  de- 
gree the  viscosity  of  the  collodions. 

VII.    RESUME  AND   CONCLUSIONS 

As  already  stated,  the  results  of  the  experiments 
just  described  complete  in  a  certain  sense  those  ob- 
tained by  M.  Vieille  in  1883,  since  they  relate  to  a 
series  of  mixtures  that  had  not  been  studied  up  to 
this  time. 

Apart  from  the  theoretical  interest  they  may  pos- 
sess, they  also  possess  a  practical  utility. 

When  it  is  desired  to  produce  a  certain  definite 
nitro-cellulose,  the  first  thing  to  determine  upon  is 
the  composition  of  the  dipping  mixture  to  be  em- 
ployed. Heretofore,  the  proportions  of  the  different 
elements,  whether  new  or  spent  acids,  were  calcu- 
lated somewhat  arbitrarily.  The  experiments,  of 
which  a  resume  has  just  been  given,  permit  a  more 
methodical  procedure  in  such  a  case. 

These  are  only  laboratory  experiments,  it  is  true; 
and  in  practice  a  thousand  causes,  more  or  less  well 
understood,  arise  to  influence  final  results.  Some 
supplementary  experiments  have  been  made  to  as- 
certain how  these  known  causes  tend;  but  it  would 
be  rash  to  assert  that  it  would  be  possible,  on  the 
strength  of  the  data  afforded  by  these  experiments, 
to  obtain  with  certainty  a  product  of  which  all  the 
qualities  were  predetermined, 


THE  NITRATION  OF  COTTON  I  53 

However,  the  great  similarity  of  the  results  ob- 
tained in  the  three  series  of  experiments,  each  of 
which  approaches  more  nearly  than  the  preceding 
to  conditions  obtaining  in  practice,  justifies  the  be- 
lief that,  although  no  one  of  them  may  enable  us  to 
calculate  the  proportions  of  a  mixture  capable  of  pro- 
ducing a  certain  product,  nevertheless,  the  general 
trend  of  the  phenomenon  of  nitration  is  that  indi- 
cated by  the  position  and  relative  importance  of  the 
different  zones  above  referred  to. 

The  knowledge  of  this  progress  in  the  phenomenon 
of  nitration  permits  us,  then,  after  a  preliminary  trial, 
which,  besides,  is  not  undertaken  by  chance,  to 
modify,  if  necessary,  the  proportions  of  the  mixture 
first  taken,  in  such  a  way  as  to  arrive  at  a  desired  end. 

Different  considerations  serve  as  guides  in  the 
preparation  of  the  preliminary  mixture.  While  still 
keeping  within  the  zone  corresponding  to  the  prod- 
uct desired,  the  relative  proportions  of  nitric  acid 
and  water  may  be  varied  between  quite  wide  limits. 
It  is  desirable,  from  the  standpoint  of  economy,  to 
diminish  the  quantity  of  the  most  expensive  element; 
that 'is  to  say,  the  nitric  acid;  in  certain  cases,  how- 
ever, to  develop  certain  qualities  in  the  final  product, 
we  may  be  led  to  increase  it.  Finally,  if  spent  acids 
of  known  composition  are  to  be  employed,  one  mix- 
ture may  be  found  more  advantageous  than  another, 
according  to  the  relative  quantities  of  acids  to  be 
taken. 

The  acids  used,  nitric  acid  or  spent  acids,  always 
contain  nitrous  vapors  to  a  small  extent.  These 


154  SMOKELESS  POWDER 

nitrous  vapors  may,  if  present  in  sensible  quantity, 
falsify  conditions  upon  which  it  was  thought  reliance 
could  be  placed,  and  this  fact  must  be  borne  in  mind 
in  calculating  the  trial  mixture.  But  in  practice  the 
proportion  does  not  exceed  from  i  to  2  per  cent.,  and 
within  these  limits  it  may  be  admitted  that  the  pres- 
ence of  nitrous  vapors  does  not  change  results  sen- 
sibly. 

It  is  necessary,  besides,  to  bear  in  mind  that  on  ac- 
count of  the  reaction  that  takes  place  in  the  dipping- 
vats,  and  which  produces  water,  the  proportions  of 
sulphuric  acid,  nitric  acid  and  water  in  the  vats  are 
no  longer  the  same  as  those  of  the  original  mixture. 
These  alone  are  the  conditions  which  affect  the  de- 
gree of  nitration  and  are  determined  beforehand  ac- 
cording to  the  considerations  just  indicated.  The 
others,  which  must  also  be  known,  since  they  serve 
in  preparing  the  mixtures  properly  so-called,  are 
easily  deduced  by  means  of  corrections,  which  de- 
pend upon  the  size  of  the  vats,  the  relative  weight  of 
cotton  employed  each  time,  etc.,  etc.;  and  they  are 
determined  in  practice,  by  analysis,  before  and  after 
dipping,  of  a  certain  number  of  mixtures  most  com- 
monly employed. 

When  the  formula  for  a  mixture  permitting  de- 
sired results  to  be  obtained  is  thus  found,  the  choice 
of  raw  material  to  be  dipped  is  also  to  be  thought  of, 
as  well  as  temperature  of  dipping,  duration  and  tem- 
perature of  the  reaction,  etc.,  etc. 

Here  also,  the  experiments  recalled  above  may 
serve  as  a  guide  to  results  to  be  obtained. 


THE   NITRATION  OF  COTTON  155 

There  always  exist  sensible  differences  between  the 
industrial  manufacture  of  a  product  and  the  labora- 
tory process  which  serves  as  a  basis  for  it.  A  thou- 
sand causes,  varying  from  day  to  day,  arise  to  modify 
the  qualities  of  the  final  product.  At  first  one  pro- 
ceeds only  by  guess-work;  it  is  only  in  the  end,  as 
the  result  of  the  processes  followed  with  method  and 
perseverance,  that  one  becomes  able  to  define  with 
exactness  the  effect  produced  by  each  one  of  a  num- 
ber of  stated  modifications. 

With  this  line  of  thought  a  number  of  experiments 
were  made  at  the  Angouleme  laboratory  upon  the 
production  of  nitro-celluloses.  Much  still  remains 
to  be  done,  but  the  results  obtained  already  permit  a 
more  methodical  procedure  than  in  the  past. 


APPENDIX   IV 

THE   DEVELOPMENT   OF   SMOKELESS   POWDER* 
By  Lieutenant  JOHN  B.  BERNADOU,  U.  S.  Navy 

THE  systematic  development  of  improved  ballistic 
properties  from  progressive  explosives  constitutes 
one  of  the  most  important  ordnance  problems  of  the 
present  day.  The  idea  is  beginning  to  gain  ground 
among  us  that  hereafter  we  must  look  to  the  powder, 
as  well  as  to  the  gun,  in  our  efforts  to  increase  the 
rapidity  of  flight  and  the  penetrative  power  of  pro- 
jectiles; that  we  must  consider  the  source  of  energy 
at  our  disposal  conjointly  with  the  apparatus  whose 
function  it  is  to  convert  that  energy  into  useful  work. 

So  long  as  the  art  of  powder-making  remained  at 
a  standstill — as  it  practically  did  for  several  centuries 
— while  the  practices  of  alchemy,  rather  than  the  prin- 
ciples of  chemistry,  may  be  said  to  have  controlled 
the  manufacture  of  all  explosives,  the  best  that  could 
be  done  was  to  follow  the  progress  of  mechanics  in 
efforts  to  effect  ordnance  improvement;  guns  were 
built  and  powders  were  found  to  fire  from  them.  To- 

*  Abstract  of  lecture  delivered   before  the  U.  S.    Naval   War 
College,  July  20,  1897. 

156 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    I  57 

day,  however,  not  only  is  the  composition  of  powder 
undergoing  modification,  but  new  explosive  com- 
pounds, the  development  of  which  is  based  upon 
chemical  discovery,  are  coming  into  general  use;  the 
results  of  investigations  into  the  chemical  and  physical 
properties  of  explosives,  systematized  and  coordi- 
nated by  the  methods  of  mathematical  analysis,  have 
so  increased  our  knowledge  of  ballistics,  that  de- 
signers of  ordnance  are  forced  to  accept  new  condi- 
tions as  factors  of  prime  importance  in  the  attain- 
ment of  ballistic  effect. 

For  purposes  of  comparison,  the  old  forms  of  pow- 
der, such  as  black  gunpowder,  may  be  regarded  as 
imperfect  mechanical  mixtures  of  particles  of  the  ma- 
terials of  which  the  powder  is  composed;  the  new  ex- 
plosives, as  very  intimate  mixtures  of  the  atoms  of 
those  elements  from  the  union  of  which  into  molecules 
the  substance  of  the  explosive  is  formed.  When  the 
old  powder  is  employed  as  a  fine  dust,  it  burns  with 
great  speed  and  violence;  when  agglomerated  into 
grains*  it  burns  in  a  slow,  progressive  manner.  If  the 
grains  of  the  old  powders  become  disintegrated  before 
they  are  completely  consumed,  through  effects  of  heat 
and  gas  pressure  developed  in  the  bore  of  the  gun,  the 
grains  crumble  away;  pressures  become  violent  and 
regular  progressive  combustion  ceases  to  obtain. 
Similar,  but  not  identical,  conditions  exist  for  the 
new  explosives.  In  the  form  of  dust  they  burn  with 

*  By  "  grain  "  is  to  be  understood  any  regular  form,  flat  strips, 
rods,  cubes,  etc. 


158  SMOKELESS  POWDER 

exceeding  rapidity  and  great  violence;  when  all  the 
particles  are  decomposed  simultaneously,  they  deto- 
nate; by  building  them  up  into  dense  grains  they  may 
be  made,  under  favorable  conditions,  to  burn  pro- 
gressively. 

It  was  obvious  from  the  start  that  many  advan- 
tages were  to  be  obtained  by  the  substitution  of  the 
new  explosives  for  the  old  as  progressive  powders. 
The  former  burned  up  completely,  leaving  no  resi- 
due. Many  of  them  made  no  smoke.  Other  condi- 
tions being  equal,  these  two  qualities  alone  would 
have  been  sufficient  to  justify  their  general  adoption. 
But  other  conditions  were  not  equal.  Up  to  a  few 
years  ago  the  fact  remained  that  no  positive,  certain 
means  of  making  nitro-explosives  burn  progressively 
had  been  found.  All  known  precautions  could  be  ob- 
served in  the  preparation;  they  could  be  built  up  into 
dense  grains  with  the  greatest  possible  care;  yet, 
every  now  and  then  a  charge  of  the  powder  would 
detonate;  that  is,  instead  of  burning  progressively,  in 
accordance  with  the  finished  form  of  its  grains,  it 
would  burn  as  the  dust  from  which  the  grains  were 
built  up.  A  gun  would  be  shattered,  perhaps  a  life 
or  two  lost,  and  then  all  confidence  in  the  new  ma- 
terial would  disappear,  the  chosen  line  of  develop- 
ment would  be  abandoned;  no  fundamental  facts 
would  be  left  unchallenged  to  anchor  new  hopes 
upon. 

Until  some  way  could  be  found,  then,  of  firing  a 
nitro-compound  from  a  gun  with  positive  assurance 
that  detonation  would  not  occur,  there  could  be  no 


THE  DEVELOPMENT  Of  SMOKELESS  POWDER    159 

change  from  the  old  powders  to  the  new.  This  as- 
surance was,  however,  obtained  by  the  discovery  that 
nitro-cellulose,  colloided  and  formed  into  grains  of 
regular  size,  would  in  all  cases,  if  ignited  in  a  closed 
space,  burn  away  in  a  progressive  manner,  at  a  rate 
proportional  to  the  form  and  dimensions  of  the  grains 
and  to  the  conditions  of  their  confinement.  Two 
proofs  made  the  fact  certain  that  colloids  would  not 
detonate;  first,  that  the  grains  of  colloid  powders 
which  were  shot  out  of  the  gun  without  being  com- 
pletely consumed,  preserved  the  original  shapes,  in  re- 
duced dimensions,  of  the  grains  of  which  the  powder 
charge  was  primarily  composed;  second, that  not  tens, 
nor  hundreds,  but  thousands  of  rounds  of  colloid  pow- 
ders, fired  in  guns  or  exploded  in  closed  vessels,  de- 
veloped in  every  case  pressures  that  could  be  shown 
to  correspond  rationally,  in  accordance  with  the 
theory  of  progressive  combustion,  to  size  and  form 
of  grains  and  to  dimensions  of  gun-chamber  or  ex- 
plosion-bomb. To  make  these  facts  certain,  pres- 
sures were  carried  up  beyond  the  33,ooo-lb.  limit  al- 
lowed for  cannon;  and  in  explosion-bombs  to  well 
beyond  100,000  Ibs.  per  square  inch. 

Now,  as  the  only  certain  means  yet  found  of  avoid- 
ing detonation  and  of  assuring  progressive  combus- 
tion is  through  the  colloiding  of  nitro-cellulose,  and 
as  nitro-cellulose  alone  can  be  colloided,  it  follows 
that  we  are  definitely  limited  in  our  choice  of  ma- 
terial for  progressive  powders  to  a  certain  prepara- 
tion of  nitro-cellulose.  It  is  true  that  a  number  of 
substances,  such  as  nitre-glycerin  and  nitrates  of 


l6o  SMOKELESS  POWDER 

metallic  bases,  may  be  distributed  in  minute  particles 
throughout  the  body  of  the  colloid,  and  that  im- 
munity from  simultaneous  detonation  may  be  se- 
cured for  the  particles  so  distributed;  but  they  all  re- 
main uncombined  in  the  colloid — the  nitrates,  as  the 
sand  or  minute  shells  in  the  body  of  a  sponge;  the 
nitro-glycerin,  as  the  water  in  the  pores  of  the 
sponge.  It  is  desired  to  emphasize  by  this  compari- 
son the  fact  that  all  the  new  powders,  without  excep- 
tion, must  be  built  up  from  some  form  of  colloid 
nitro-cellulose,  whether  they  contain  other  ingredi- 
ents or  not.  Thus,  in  the  case  of  those  powders  con- 
taining nitro-glycerin  we  may  reduce  the  percentage 
of  nitro-glycerin  to  zero;  that  is,  we  may  eliminate 
it.  If  we  were  to  remove  the  colloid  nitro-cellulose 
from  such  a  powder  we  would  have  remaining  nitro- 
glycerin,  which  would  detonate  in  the  gun  upon  the 
attempt  to  fire. 

Nitro-cellulose,  which  is  usually  prepared  by  dip- 
ping cotton  into  nitric  acid,  possesses  a  property 
which  the  cotton,  before  dipping  into  acid,  does  not, 
i.e.,  of  dissolving  in  a  number  of  substances.  One 
of  these  is  acetone,  a  volatile  fluid,  with  a  character- 
istic pungent  and  aromatic  odor,  somewhat  suggest- 
ing common  alcohol  in  appearance  and  properties. 
Another.solvent  for  a  different  kind  of  nitro-cellulose 
is  a  mixture  of  ether  and  alcohol.  If  the  clear  liquids 
which  constitute  the  solutions  in  these  substances  be 
evaporated,  there  will  be  obtained,  not  the  nitrated 
cotton,  in  its  original  fibrous  form,  but  first,  a 
syrupy  liquid,  then  a  jelly,  and  finally,  as  dryness  is 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER   l6l 

approached,  a  solid  translucent  mass,  varying  in  color 
according  to  the  variety  of  nitro-cellulose  from  which 
it  is  prepared,  from  a  straw-yellow  to  a  chocolate- 
brown,  and  generally  suggesting,  in  its  various  forms, 
tortoise-shell.  To  such  a  substance  the  appella- 
tion colloid,  from  its  glue-like  consistency,  has  been 
applied. 

The  general  name  for  the  material  produced  by 
steeping  cellulose  into  nitric  acid  is  nitro-cellulose. 
One  of  its  common  forms  is  gun-cotton.  Chemists 
are  well  aware  that  there  are  many  different  kinds  of 
nitro-cellulose,  but  just  how  many  there  are  no  one 
has  as  yet  even  been  able  to  predict,  the  exact  com- 
position of  cellulose  and  of  its  nitro-derivatives  re- 
maining among  the  yet  unsolved  mysteries  of  nature. 
Three  forms  were  originally  assigned  to  it,  the  mono-, 
di-  and  tri-,  just  as  there  were  the  three  forms  of 
mono-,  di-  and  trinitro-glycerin.  A  later  investi- 
gator (Eder)  succeeded  in  proving  the  existence  of 
six.  The  authority  of  to-day  upon  the  subject,  whose 
views  are  now  generally  accepted  (Vieille),  has  form- 
ulated eight.  Now,  just  as  there  are  many  varieties 
of  nitro-cellulose,  so  there  are  many  varieties  of  col- 
loids. The  nitro-celluloses  themselves  all  look  alike; 
in  their  common  pulped  form  they  suggest  fine  white 
flour.  They  can  be  distinguished  from  one  another 
with  ease  by  the  readiness  with  which  some  of  them 
go  into  solution  in  certain  solvents,  while  others  re- 
main undissolved  in  these  solvents  like  so  much  sand. 
The  fact  that  they  possess  such  different  properties 
is  accounted  for  in  practice  by  proven  differences  in 


1 62  SMOKELESS  POWDER 

chemical  composition.  It  suffices  here  to  state  that 
there  are  a  number  of  different  varieties  of  the  sub- 
stance which  form  a  number  of  different  colloids. 
The  question  of  composition  will  be  considered  later 
in  relation  to  the  gases  resulting  from  the  combus- 
tion of  nitro-compounds. 

We  are  familiar  with  the  kind  of  nitre-cellulose 
used  for  detonating  purposes — gun-cotton.  We  are 
also  familiar  with  a  form  of  colloid  in  common  use  to- 
day as  a  material.  I  refer  here  to  celluloid,  now  very 
generally  employed  for  the  manufacture  of  a  great 
number  of  useful  articles.  The  nitro-cellulose  from 
which  celluloid  is  prepared  may  be  made  by  steep- 
ing cotton  in  weak  acids,  and  is  rather  a  combustible 
than  an  explosive;  it  is  a  very  different  substance 
from  the  high  explosive,  gun-cotton,  which  is  pre- 
pared from  cotton  by  the  use  of  strong  acids.  One  sol- 
vent used  to  make  celluloid  is  a  mixture  of  ether  and 
alcohol;  the  same  solvent  has  no  effect  upon  gun-cot- 
ton, to  dissolve  which  acetone  must  be  used.  We 
have,  then,  two  different  types  of  colloid  to  start 
with — celluloid  (formed  from  weakly  nitrated  cellu- 
lose by  the  use  of  ether-alcohol),  and  the  acetone  col- 
loid of  gun-cotton.  It  may  be  stated  here  that  these 
two  types  of  colloids  represent  all  that  is  important 
in  relation  to  colloid  material  for  the  manufacture  of 
smokeless  powder,  as  the  matter  has  been  understood 
up  to  a  very  recent  date.  The  various  colloids  of  the 
eight  varieties  of  gun-cotton  above  referred  to  range 
themselves  under  one  or  the  other  of  these  two  types. 
We  thus  have  two  classes  of  colloid  to  experiment 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER   163 

with,  as  gunpowder,  and  all  the  information  we  pos- 
sess in  relation  to  them  is  the  fact  that,  however  they 
may  burn  in  the  gun,  yet  they  will  not  detonate. 

Suppose  that  a  number  of  rounds  of  powder  are 
prepared  from  the  two  colloids,  how  will  they  act 
when  fired  from  a  gun  of  a  given  calibre?  Let  us  as- 
sume that  we  have  at  our  disposal  the  instruments 
commonly  employed  for  the  measurement  of  muzzle 
velocities  and  of  bore-pressures,  the  chronograph  and 
pressure  gauges;  we  will  then  have,  as  a  basis  of  com- 
parison, first,  the  ratios  V IP  of  velocities  to  pres- 
sures*; second,  our  personal  observations  of  other 
phenomena  attending  explosion. 

Actual  practice  shows  that  the  best  results  ob- 
tained for  the  two  powders  in  a  given  gun,  by  vary- 
ing weights  of  charge  and  dimensions  of  grain,  would 
be  about  as  follows: 

Gun-cotton-acetone  colloid V/P  =  2100/15-19; 

Celluloid  ixitro-cotton  f  colloided  with  )       v/P—o-m   /*& 
ether-alcohol [       y'^ 

Inspection  of  the  results  shows  the  existence  of  a 
pressure-range  of  from  fifteen  to  nineteen  tons  for 
the  acetone  powder;  this  means  that  while  no  detona- 
tion would  occur,  yet  that  pressures  would  jump  be- 
tween certain  limits.  Such  a  phenomenon  is  often 
observed  in  the  tests  of  brown  powders  for  heavy 

*  A  convenient  expression  for  comparing,  in  a  given  gun,  the 
ballistic  properties  of  different  progressive  powders, —  V  repre- 
senting velocities  in  foot-seconds,  and  P,  pressures  in  tons  per 
square  inch. 

f  Commonly  called  "  soluble  nitro-cellulose." 


164  SMOKELESS  POWDER 

guns.  A  powder  of  this  character  would  be  unsuitable 
for  general  use  by  reason  of  pressure  irregularity. 

Upon  firing  the  celluloid  powder  another  and  per- 
haps worse  inconvenience  would  be  met  with.  Con- 
siderable smoke  would  be  developed  and  the  interior 
of  the  bore  would  be  found  lined,  after  each  round, 
with  a  heavy  coating  of  soot,  which,  after  one  or  two 
shots  had  been  fired  and  the  gun  had  become  heated, 
would  ignite  after  each  succeeding  round  upon  in- 
gress of  fresh  air  on  opening  of  the  breech,  thereby 
producing  flaming  at  breech  and  muzzle. 

Obviously,  as  gunpowder,  neither  the  one  nor  the 
other  form  of  colloid  is  suitable.  If  they  are  to  be 
employed  they  must  be  improved.  Irregularity  in 
pressures  from  the  gun-cotton-acetone  colloid  is  due 
to  brittleness;  if  we  are  to  use  this  material  we  must 
devise  some  means  of  toughening  it.  The  celluloid 
does  not  contain  enough  oxygen  to  consume  its  sub- 
stance into  gases;  to  use  the  latter  we  must  put  more 
oxygen  into  it. 

The  original  phases  of  the  colloid  powder  question 
thus  present  themselves.  Neither  the  one  nor  the 
other  form  of  colloid  proving  suitable  for  direct 
manufacture  into  powder,  people  began  to  try  to  im- 
prove them  by  combining  them,  or  by  adding  foreign 
substances  to  them.  It  was  well  understood  that  no 
form  of  gun-cotton,  however  highly  nitrated,  con- 
tained enough  oxygen  to  effect  its  own  complete 
combustion — the  conversion  of  its  carbon  into  the 
higher  oxide  of  carbon,  CO2.  The  first  idea  of  the 
experimenter  was  to  add  enough  oxygen  to  the  nitro- 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    l6$ 

cellulose  to  thus  complete  its  combustion,  and  this 
unfortunate  attempt  led  to  many  years'  delay  in  the 
development  of  smokeless  powder.  It  started  in- 
vestigators off  upon  a  wrong  track;  complete  com- 
bustion was  one  thing,  and  the  work  necessary  to  de- 
velop highest  velocity  with  lowest  bore-pressure,  an- 
other. 

With  the  purpose,  then,  of  improving  ballistic 
qualities  of  powders  by  causing  them  to  consume 
completely  and  to  develop  regular  pressures,  experi- 
menters in  different  countries  began  to  try  the  effect 
of  introducing  into  the  colloid  various  foreign  sub- 
stances,— generally,  oxidizing  agents,  such  as  ni- 
trates of  metallic  bases;  sometimes,  when  the  mix- 
tures became  too  violent  in  their  action,  a  substance 
rich  in  carbon,  called  a  deterrent,  was  added.  Such 
work  was  a  good  deal  like  groping  in  the  dark. 
There  was  no  method  in  it.  But  there  was  one  great 
incentive  to  keeping  it  up,  viz.,  the  fact  thereby  es- 
tablished that  the  addition  of  these  nitrates  to  the 
colloids  actually  increased  the  velocity  developed  for 
a  given  bore-pressure,  whatever  the  inconveniences 
attendant  upon  the  employment  of  these  mixtures  as 
powders  may  have  been.* 

To  establish  a  comparison  between  the  ballistic 
efficiencies  of  the  two  types  of  pure  colloids  above 

*  The  increase  in  muzzle  velocities  for  a  given  bore-pressure  to 
be  attained  by  incorporating  certain  quantities  of  metallic  ni- 
trates, nitro-glycerin,  etc.,  into  the  body  of  the  colloid,  con- 
stitutes a  special  phase  of  development  of  progressive  powders, 
which  will  be  discussed  in  a  subsequent  paper. 


1 66  SMOKELESS  POWDER 

cited,  and  of  certain"  compound  colloid  powders  into 
the  substance  of  which  metallic  nitrates  or  other  oxy- 
gen-carriers are  incorporated,  the  tabular  record  of 
performances  of  powders  of  these  classes  is  submitted 
on  page  167.  Note  is  made  therein  of  objectionable 
features  developed  for  each  of  the  explosives  named. 

Referring  to  the  table  we  find  powders  A  and  B 
with  properties  as  already  described.  -  The  K,  BN, 
and  cordite  all  make  good  ballistic  showings,  giving 
velocities  greater  by  about  300  ft.  sec.  for  a  de- 
veloped pressure  than  the  former. 

The  last  line  of  the  table  shows  that  each  of  the 
powders  possesses  certain  unfavorable  qualities  which 
militate  against  its  adoption  for  service  use.  The 
gun-cotton  acetone  colloid  develops  irregular  pres- 
sures; the  ether-alcohol  colloid  of  soluble  nitro- 
cellulose deposits  soot;  the  K  and  BN  produce  some 
smoke  and  bore-deposit.  Cordite  contains  a  volatile 
liquid,  nitre-glycerin,  which  develops  great  heat 
upon  combustion.  Now  the  development  of  highest 
velocity  at  lowest  pressure  is  most  important,  even 
if  obtained  at  the  expense  of  the  production  of  cer- 
tain partially  unfavorable  conditions;  but  there  was 
a  further  incentive  to  progress  at  this  stage  of  de- 
velopment— the  fact  there  had  been  found  a  form  of 
pure  colloid,  unadulterated  by  admixture  with  other 
substances,  which,  while  developing  high  velocities 
at  moderate  pressures,  possessed  the  full  round  of 
good  qualities  necessary  in  a  service  powder. 

The  end  sought  for  in  the  development  of  gun- 
powder is  the  attainment  of  the  capability  of  deliver- 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    l6/ 


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SMOKELESS  POWDER 


ing  most  accurately  in  a  given  interval  of  time  the 
greatest  number  of  most  powerful  blows;  this  result 
to  be  effected  with  minimum  risk  to  gunners  and  with 
least  possible  injury  to  gun.  Hereby  is  implied  the 
fulfilment  of  a  number  of  important  independent 
conditions,  no  one  of  which  may  be  overlooked  in  the 
effort  to  successfully  accomplish  the  object  sought. 
These  conditions  correspond  to  qualities  possessed 
by  a  powder,  and  may  be  given,  with  their  opposites, 
a  general  grouping  under  headings  as  follows: 

TABLE  II 

QUALITIES    OF    POWDERS 


i 

2 

3 

4 

5 

Positive  -j 

Non-liability 
to 
detonation 

Devel'pment 
of  minimum 
heat 

Formation  of 
minimum 
residue 

Good    keep- 
ing   quali- 
ties 

Maximum 
propulsive 
effect 

Negative  \ 

Detonation 

Erosion 

Smoke  and 
bore-deposit 

Decomposi- 
tion 

Low  value 
of  V/P 

The  first  condition  is  of  paramount  importance 
and  limits  us  to  the  employment  of  a  colloid  material. 
The  second  represents  the  fact  that  the  greater  the 
heat  developed  the  greater  the  wearing  away  of  the 
inner  surface  of  the  bore.  The  third  requirement 
means  obviation  of  bore-deposit,  which  operates  to 
reduce  rapidity  of  fire  by  necessitating  more  or  less 
frequent  sponging,  and  to  diminish  accuracy  of  prac- 
tice through  the  formation  of  smoke.  The  fourth  re- 
quirement, stability,  is  all-important,  when  we  re- 
member that  the  ship  must  carry  safely  her  store  of 
powder  for  at  least  a  cruise,  and  for  the  reason  that 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    169 

when  powders  begin  to  decompose  they  lose  their 
homogeneity  and  crumble — which  means  an  end  to 
regular-pressure  development. 

Let  us  now  take  up  requirement  fifth — the  attain- 
ment of  maximum  propulsive  effect — and  see  what  it 
leads  to.  What  causes  the  expulsion  of  the  projec- 
tile from  the  gun?  The  expansion  of  powder-gases. 
What  limits  our  employment  of  the  expansive  force 
of  these  gases?  The  attainment  of  the  limiting  bore- 
pressure,  this  limit  being  commonly  set  at  fifteen  tons 
per  square  inch.  What  represents  the  greatest 
amount  of  work  in  the  form  of  velocity?  The  great- 
est amount  of  gas-expansion  in  the  gun  behind  the 
projectile. 

We  desire,  then,  the  greatest  amount  of  gas  ex- 
pansion, but  we  are  limited  as  to  the  rate  of  this  ex- 
pansion; that  is,  we  must  not  let  it  develop  in  the 
bore  a  pressure  greater  than  fifteen  tons  in  the  gun- 
chamber  or  upon  the  interior  walls  of  the  piece.  This 
is  tantamount  to  saying  that  to  produce  maximum 
velocity  we  require  the  evolution,  at  a  suitable  lim- 
ited rate  of  expansion,  of  the  greatest  possible 
volume  of  gas,  the  expansion  of  the  gas  constituting 
under  these  conditions  the  propelling  impulse. 

It  may  be  stated  here  that  we  possess,  within  limits, 
the  power  of  controlling  the  rate  of  combustion  of 
colloid  powders  -by  varying  certain  conditions  re- 
lating to  combustion,  the  principal  of  which  are  (i) 
the  size  of  the  grains  of  which  the  charge  is  com- 
posed, (2)  the  volume  of  the  powder-chamber,  (3) 
the  length  of  the  bore  of  the  gun,  (4)  the  weight  of 


I/O  SMOKELESS  POWDER 

the  projectile.  Granting,  then,  that  we  possess 
within  limits  the  capability  of  controlling  the  rate  of 
evolution  of  the  powder-gases,  we  are  led  to  the  fol- 
lowing conclusion:  that  the  best  smokeless  powder 
is  that  stable  colloid  which,  for  a  given  weight  of  its 
substance,  evolves  in  the  bore  of  the  gun  at  the  most 
suitable  rate  of  evolution  and  expansion,  the  greatest 
volume  of  gas,  the  said  evolution  being  accompanied 
with  the  development  of  the  least  heat. 

We  are  led  by  this  deduction  to  regard  the  action 
of  the  powder  from  a  new  standpoint.  Besides  con- 
sidering what  a  powder  is  composed  of,  wre  must  now 
consider  what  gases  it  is  converted  into  upon  decom- 
position, and  what  volumes  of  these  gases  it  gener- 
ates. Most  important  of  all,  it  leads  us  to  conduct 
experiments  for  the  purpose  of  ascertaining  what 
colloid  will,  for  a  given  weight  of  its  substance,  liber- 
ate the  greatest  volume  of  gases. 

Here  was  one  starting  point  for  a  series  of  experi- 
mental researches  culminating  in  the  discovery  of  an 
efficient  smokeless  powder.  Another  line  of  experi- 
mental approaches  to  the  same  end  connected  the 
efforts  to  toughen  the  substance  of  colloid  films  con- 
taining sufficient  oxygen  to  effect  their  own  com- 
plete combustion,  with  a  view  to  the  attainment  of 
increased  regularity  in  developed  pressures;  a  third 
related  to  the  determination  of  the  causes  of  certain 
ballistic  phenomena  hitherto  unexplained,  e.g.,  that 
acetone  colloids  developed,  in  some  cases,  greatly 
improved  ballistic  qualities,  after  the  lapses  of  periods 
of  from  six  to  twelve  months  from  time  of  manufac- 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    I /I 

ture.  These  several  lines  of  experimental  investiga- 
tion proved  in  the  end  to  converge  towards  the  at- 
tainment of  a  common  result — the  development  of  a 
special  form  of  nitro-colloid  that  possessed  the 
toughness  and  therefore  the  regularity  of  burning  of 
celluloid,  and  that  contained  enough  oxygen  to  con- 
vert its  substance,  upon  ignition,  into  wholly  gaseous 
products — which  the  celluloid  did  not — and  that 
liberated  not  only  the  greatest  volume  of  powder- 
gases  at  the  most  suitable  rate,  but  the  greatest 
volume  of  gases  that  can  be  evolved  by  any  colloid 
at  any  rate  of  combustion,  whether  these  colloids 
contained  or  did  not  contain  nitro-glycerin,  metallic 
nitrates  or  other  substances. 

The  questions  now  present  themselves:  in  what 
ways  do  we  possess  the  control  of  kind  and  amount 
of  gases  evolved  upon  the  combustion  of  nitro- 
cellulose and  of  its  colloids;  how  does  the  constitu- 
tion of  these  gases  vary;  what  are  they? 

It  has  been  already  stated  'that  the  exact  chemical 
formulae  for  cellulose  and  its  nitro-derivatives  have 
not  yet  been  written.  That  for  cellulose  may  be  ap- 
proximately expressed  as  C6nUlonO5H ,  where  n  is  an 
undetermined  or  indeterminate  numerical  quantity. 
When  cellulose  is  steeped  in  nitric  acid  or  in  a  mix- 
ture of  nitric  and  sulphuric  acids,  it  is  converted  into 
the  substance  the  composition  of  which  may  be  ex- 
pressed asasC6wHIOW_^Os«(NO2)^.  These  two  expres- 
sions, C6wHIOWO5«  and  C6wHIO«.rtWO5W(NO2)aw,  may  be 
considered  in  comparison  with  one  another.  But 
contain  the  same  quantity  of  carbon;  the  quanti- 


I72  SMOKELESS  POWDER 

ties  present  of  the  other  elements  are  changed  by 
nitration;  an  atoms  of  hydrogen  are  displaced  by 
an  equivalents  of  a  combination  of  nitrogen  and 
oxygen  (NO2).  This  additional  oxygen  from  the 
NO2  acts  to  supply  the  energy  that  converts  the 
cellulose  into  an  explosive,  and  enters  into  its  sub- 
stance in  combination  with  a  certain  quantity  of  nitro- 
gen. Why  it  carries  the  nitrogen  with  it  we  do  not 
know,  but  it  is  a  chemical  fact  that  it  does  so — the 
fact  upon  which  the  designation  of  the  new  ex- 
plosives as  nitro-derivatives  or  nitro-explosives  is 
based. 

Upon  the  ignition  of  the  nitro-cellulose  or  its 
colloid  the  nitrogen  is  set  free;  the  hydrogen  com- 
bines with  its  equivalent  of  oxygen  and  appears  in 
the  air  as  steam;  the  remaining  oxygen  unites  with 
the  carbon  to  form  gaseous  oxides  of  carbon.  If 
there  be  not  enough  oxygen  to  consume  all  the  car- 
bon into  gas,  part  of  the  latter  is  deposited  as  soot; 
this  result  was  obtained  in  the  attempt  to  employ 
celluloid  as  gunpowder.  If  there  is  enough  oxygen 
to  consume  all  the  carbon  into  gases,  we  have,  as 
products  of  combustion,  a  mixture  of  the  gaseous 
oxides  of  carbon,  of  which  there  are  two,  CO2  and 
CO. 

The  property  possessed  by  carbon  of  combining 
at  high  temperatures  with  intense  energy  with 
oxygen,  to  form  gaseous  oxides,  is  the  fact  upon 
which  the  practical  development  of  explosives  de- 
pends; there  are  many  explosives  that  contain  neither 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    173 

carbon  nor  oxygen,  but  with  these  we  have.as  yet  no 
practical  relations  in  ordnance  matters. 

It  has  been  stated  already  that  the  attempt  to  ob- 
tain what  is  called  complete  combustion  for  nitro- 
cellulose colloids  by  incorporating  oxidizing  agents 
into  them  had  misled  investigators,  who  confounded 
the  attainment  of  complete  combustion  with  the  de- 
velopment of  maximum  velocity  at  lowest  pressure. 
"  Complete  combustion  "  means  the  conversion  of  all 
the  carbon  into  the  higher  oxide  of  carbon — car- 
bonic acid,  CO2 — a  dense  gas  about  1.9  times  as 
heavy  as  the  air,  the  formation  of  which  is  accom- 
panied with  the  development  of  a  high  degree  of  heat. 
The  complete  combustion  of  carbon  into  carbonic 
acid  gas  with  the  corresponding  evolution  of  a  great 
amount  of  heat  is  the  characteristic  of  the  combus- 
tion of  nitro-glycerin.  The  lower  oxide  of  carbon, 
CO,  is  a  gas  much  less  dense  than  carbonic  acid,  pos- 
sessing a  density  of  about  1.4  times  that  of  air.  Sup- 
pose that  we  have  a  given  weight  of  a  compound  of 
carbon  and  oxygen,  with  the  elements  taken  in  such 
proportions  as  to  produce,  on  ignition,  complete 
combustion  into  carbonic  acid  gas,  CO2,  with  the  ac- 
companying evolution  of  a  large  amount  of  heat; 
let  us  also  suppose  that  we  have  an  equal  weight  of 
compound  of  the  same  elements  in  such  proportions 
as  to  develop,  on  ignition,  the  lower  oxide  of  carbon, 
carbonic  oxide,  CO;  then,  the  latter  compound,  de- 
veloping the  lower  oxide,  would  liberate  a  volume  of 
gas  nearly  1.9/1.4=1.36  times  greater  than  the 
former.  The  greater  heat  produced  by  the  forma- 


174  SMOKELESS   POWDER 

tion  of  the  carbonic  acid  gas  would  cause  the  volume 
of  that  gas  evolved  to  be  the  more  expanded,  but, 
at  the  same  time,  and  this  is  a  fact  of  crucial  impor- 
tance in  the  present  work,  the  greater  heat  would 
cause  the  gas  to  be  generated  at  a  more  rapid  rate, 
in  fact,  at  an  extremely  rapid  rate;  and  what  we  re- 
quire is  a  low,  regular  rate  of  gas  evolution  to  pre- 
vent our  exceeding  at  any  time  the  set  limit  of  per- 
missible bore-pressure. 

In  our  effort  to  generate  from  colloid  nitro-cellu- 
lose  the  greatest  volume  of  gas  at  the  most  gradual 
rate  of  expansion,  we  must  seek,  then,  (i)  to  avoid 
the  formation  of  CO2  when  CO  may  be  formed  in 
lieu  thereof;  (2)  to  avoid  the  formation  of  free  car- 
bon; and  (3)  to  generate  the  maximum  volume  of  the 
lower  carbon  oxide.  If  we  give  due  consideration 
to  the  amounts  of  water  and  of  nitrogen  formed 
simultaneously  with  the  oxides  of  carbon,  we  shall 
find  that  the  form  of  nitro-cellulose  developing  the 
greatest  volume  of  gas  at  the  most  suitable  rate,  cor- 
responds to  the  formula  C30H38(NO2)12O25,  which 
breaks  up  on  decomposition  into  30  CO  +  19 
H2O  +  12  N. 

This  material  is  a  new  type  of  nitro-cellulose,*  de- 
veloped by  experiment  to  meet  ballistic  require- 

*  This  special  form  of  nitro-cellulose,  which  corresponds  to  a 
content  of  nitrogen  of  12.44  per  cent,  and  which  was  first  devel- 
oped in  Russia  by  the  eminent  chemist,  Professor  D.  Mendeleef, 
has  been  independently  developed  at  the  Torpedo  Station, 
through  the  study  of  effects  of  variation  of  times  of  immersion, 
temperatures  of  nitration  and  of  washing,  and  strength  of  acids 
employed  in  the  nitration  of  cellulose. 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    1?$ 

merits,  which  contains  just  enough  oxygen  to  convert 
its  substance  into  a  gaseous  body.  Its  formation 
from  cellulose  depends  upon  strengths  of  nitric  and 
sulphuric  acid,  temperatures  of  reaction  and  time  of 
immersion  of  the  cellulose  in  the  acids  from  which  the 
material  is  prepared.  With  ether-alcohol  it  forms  a 
colloid  that  possesses,  on  the  one  hand,  the  tough- 
ness, and  therefore  the  capability  of  development  of 
regular  pressures,  of  celluloid;  and  on  the  other  the 
capability  of  consuming  into  wholly  gaseous  prod- 
ucts that  characterizes  the  gun-cotton  acetone 
colloid;  while  as  a  powder  it  develops,  with  present 
types  of  guns,  excellent  values  of  V IP  of  about 
2400/16.  Briefly,  it  may  be  described  as  a  celluloid 
containing  enough  oxygen  to  convert  its  substance 
(when  it  is  consumed  out  of  contact  with  the  atmos- 
phere) wholly  into  gaseous  products. 

It  was  stated  in  a  preceding  paragraph  that  the  bal- 
listic effect  produced  by  a  progressive  explosive  de- 
pended directly  upon  the  volume  of  gas  it  evolved 
upon  combustion,  but  was  not  directly  dependent 
upon  the  attainment  of  complete  combustion.  As- 
suming total  conversion  from  solids  into  gases,  and 
non-liability  to  detonation,  pyrocellulose  was  shown 
to  be  the  form  of  nitro-cellulose  best  adapted  for  con- 
version into  smokeless  powder.  As  this  material  con- 
tains only  enough  oxygen  to  convert  its  carbon  into 
carbonic  oxide,  CO — less  than  gun-cotton,  which 
converts  its  carbon  partly  into  carbonic  acid  gas, 
COo,  and  partly  into  carbonic  oxide,  CO — the  at- 
tainment of  maximum  efficiency  from  nitro-cellulose 


176  SMOKELESS  POWDER 

was  thus  shown  to  be  accomplished  through  a  reduc- 
tion from  a  maximum  to  a  mean  in  the  quantity  of 
oxygen  capable  of  being  incorporated  into  nitro- 
cellulose. 

On  the  other  hand,  it  was  stated  that  the  incor- 
poration of  certain  quantities  of  oxygen-carriers 
(nitro-substitution  compounds  other  than  nitro-cel- 
luloses,  such  as  nitro-glycerin  and  nitrates  of  metallic 
bases)  into  colloid  nitro-cellulose,  led  to  the  attain- 
ment of  an  increase  in  initial  velocity  of  projectile  for 
a  given  developed  bore-pressure.  As  nitro-glycerin 
furnishes  a  surplus  of  free  oxygen  to  aid  in  complet- 
ing the  combustion  of  the  gases  from  the  nitro-cellu- 
lose, while  the  nitrates  surrender  oxygen  on  applica- 
tion of  heat,  it  would  appear  in  this  case  that  the  at- 
tainment of  a  more  complete  combustion  led  to  im- 
provement in  ballistic  effect. 

We  are  thus  brought  face  to  face  with  a  seeming 
contradiction — how,  on  the  one  hand,  we  must  re- 
move oxygen;  how,  on  the  other,  we  must  add  oxy- 
gen to  a  progressive  explosive,  in  order  to  obtain 
maximum  ballistic  effect  therefrom.  In  order  to 
reconcile  these  apparently  contradictory  statements 
we  must  consider  the  manner  of  decomposition  of  the 
explosive  in  both  cases. 

One  chief  characteristic  of  pyrocellulose  is  its 
homogeneity.  It  represents  no  mixture  of  explosives 
and  combustibles,  such  as  are  presented  by  other 
forms  of  powders,  and  it  is  converted  directly  by  com- 
bustion into  a  set  of  gaseous  decomposition  products 
that  may  not  be  varied  in  amount  and  kind.  Under 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    If? 

these  conditions  the  ballistic  effect  of  the  expanding 
gases  from  pyrocellulose  may  be  referred  to  quantity 
of  charge,  area  of  ignition-surface,  weight  of  projec- 
tile, calibre  of  gun,  and  volume  of  powder-chamber. 
Other  conditions  affecting  developed  pressure  and 
velocity  are  bore-friction  and  resistance  of  the  pro- 
jectile to  rotation  through  inertia. 

The  gun  may  be  regarded  as  a  gas-engine  in  which 
the  walls  of  the  chamber  and  bore  form  the  cylinder; 
the  projectile,  the  piston.  The  expanding  powder- 
gases  perform  work  by  imparting  velocity  to  the  pro- 
jectile, the  inertia  of  which  they  overcome  just  as  gas 
by  its  expansion  in  the  cylinder  overcomes  the  inertia 
of  the  piston  and  the  parts  linked  thereto.  In  the  en- 
gine the  gas  is  admitted  alternately,  first  at  one  end  of 
the  cylinder  and  then  at  the  other;  in  the  gun  it  is  ad- 
mitted in  rear  of  the  projectile  but  once,  so  that  the 
gun  is  an  engine  of  a  single  stroke.  In  the  engine 
the  steam  is  admitted  into  the  cylinder  through  a 
valve,  and,  after  the  lapse  of  a  period  of  time  less  than 
that  required  for  a  full  stroke,  admission  is  cut  off 
and  wor.k  for  the  rest  of  the  stroke  is  performed  ex- 
pansively; in  the  gun  the  charge  of  powder  consti- 
tutes both  the  gas  itself  and  the  valve  that  admits  the 
gas — for  each  grain  of  powder  may  be  considered  as 
a  notch  of  opening  of  a  valve;  the  more  grains  there 
are  the  greater  the  ignition  surface,  the  greater  the 
rate  of  emission  of  gas,  or  the  greater  the  number  of 
notches  the  valve  is  open. 

The  action  of  nitro-cellulose  powder-gases  in  im- 
parting motion  to  the  projectile  is  that  of  the  gas  in 


SMOKELESS  POWDER 

the  engine  cylinder.  The  decomposition  products 
are  evolved  at  a  high  pressure,  and  act  to  propel  the 
projectile,  just  as  the  gas  or  vapor  drives  the  piston 
in  an  engine.  Thus  far  the  two  cases  are  in  parallel; 
they  differ  in  that  the  space  occupied  by  the  gas  in 
the  gun  is  constantly  increasing,  both  through  the 
effect  of  the  motion  of  the  projectile  along  the  bore 
and  from  the  increase  of  chamber  space  due  to  the 
melting  away  of  the  powder  charge,  while  space  in 
the  engine  cylinder  is  increased  through  the  motion 
of  the  piston  and  through  connection  with  the  valve 
before  cut-off.  As  shown  in  Table  I,  the  ballistic 
value  of  gun-cotton  colloided  in  acetone  (for  a  given 

2  100 
gun)  was ;  that  of  colloided  soluble  nitro-cellu- 

lose,  containing  not  enough  oxygen  to  convert  its 
carbon  wholly  into  carbonic  oxide,  CO,  was  — ^— . 

Under  similar  conditions  of  firing,  pyrocellulose  de- 

2400 
veloped  a  value  of  V/P  •     — g-.     It  may  be  urged 

that  the  ballistic  superiority  of  the  latter  colloid  as 
compared  with  that  of  the  two  former  is  not  wholly 
attributable  to  character  and  volume  of  evolved  gases, 
as  the  acetone  colloid  is  brittle,  and  that  prepared 
from  soluble  nitro-cellulose  is  somewhat  brittle,  and 
deficient  in  oxygen,  while  pyrocelluloid  is  of  a  tough, 
leathery  consistency,  capable  of  withstanding  high 
pressures  without  premature  disintegration.  Never- 
theless, as  these  colloids  prove  inferior  to  the  pyro- 
colloids  for  lower  pressures  of  about  10  tons  per 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    1/9 

square  inch,  at  which  the  effects  of  brittleness  are  not 
perceptible,  and  for  which  they  all  afford  pressures 
regularly  proportional  to  develop  velocities,  it  re- 
mains that  magnitude  of  volume  of  evolved  gases  is 
a  factor  of  prime  importance  in  the  attainment  of  bal- 
listic efficiency. 

COMPOSITE   POWDERS 

The  results  of  incorporating  an  oxidizing  agent  or 
oxygen-carrier  into  colloids  merit  special  study.  Sup- 
pose that  a  given  nitro-cellulose  be  colloided  and 
formed  into  strips  of  a  number  of  definite  thicknesses. 
If  these  strips  be  collected  separately  and  dried,  we 
may  prepare  from  them  series  of  rounds,  each  series 
composed  of  different  weights  of  strips  of  some  one 
thickness.  If  the  length  and  breadth  of  the  strips  be 
great  in  relation  to  their  thickness,  we  need  consider 
only  the  latter  element  of  dimension  in  relation  to 
their  mode  of  combustion.* 

*  We  have  (Glennon,  Interior  Ballistics,  chap.  VI,  pp.  59,  60) 


where  y  is  the  fractional  part  of  the  least  dimension  of  the  grain 
burned  up  to  any  moment;  <p(y)  the  fractional  part  of  the  whole 
grain  burned  up  to  the  same  moment;  and  or,  y,  and  ju,  constants 
depending  upon  the  form  of  the  grain. 

If  the  grain  be  a  rectangular  parallelepiped  with  a  square  base, 
and  the  altitude  as  the  least  dimension,  we  have 

.        2x  +  X*  x9 

a  =  i  -\-  2x,  A  =  = 


i  -j-  2x  '  I  4*  ft*' 

where  x  is  the  ratio  of  the  altitude  to  the  side  of  the  base." 

Applying  the  above  to  the  present  case  we  find  that  if  the  alti- 


180  SMOKELESS  POWDER 

Upon  firing  series  of  rounds  of  the  several  powders 
from  a  given  gun  we  obtain  the  following  results  as 
to  their  manner  of  explosive  action: 

i. — Strips  of  over  a  certain  mean  thickness  will  be 
only  partly  consumed  in  the  bore;  the  unconsumed 
remnants  will  be  projected  burning  from  the  gun,  to 
be  quenched  in  the  cool  outer  air,  where  they  fall  un- 
consumed to  the  ground  and  may  be  picked  up  at 
various  distances  from  the  piece  in  front  of  the  muz- 
zle, possessing  the  original  form  (in  reduced  dimen- 
sions) of  the  grains  of  which  the  charge  was  origin- 
ally composed.  Such  powders  develop  low  bore  pres- 
sures and  afford  low  muzzle  velocities.  In  point  of 
work  performed  they  are  equivalent  to  smaller 
charges  of  quicker  powders.  It  may  be  remarked 
that  no  work  is  done  in  raising  the  temperature  of 
the  unconsumed  portions  of  the  grains,  for  if  the  tem- 
perature of  the  latter  be  raised  but  a  few  degrees,  the 
ignition  point  of  the  explosive  is  reached  and  its  sub- 
stance would  wholly  disappear. 

2. — Strips  of  under  a  certain  mean  thickness  are 
totally  consumed  in  the  gun.  They  develop  high 
pressures  for  low  velocities.  The  thinner  the  strips 
the  less  the  weight  of  charge  required  to  develop  the 

tude  be  considerably  diminished  (x  approaches  zero)  we  have  the 
case  of  the  thin  plate;  and  that  the  constants  approach  the  values 

a=  i,  A.  =  o,  )JL  =  o, 

or  000  =  y. 

But  y  depends  alone  on  the  thickness  of  the  plate,  therefore 
the  speed  of  combustion  of  a  plate  is  a  linear  function  of  its  least 
dimension. 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    l8l 

limiting  permissible  pressure,  on  account  of  the 
greater  initial  surface  presented  by  the  thinner  strips, 
which  occasions  a  high  initial  gas  development. 

3. — A  certain  mean  thickness  of  strip  will  be  found, 
for  which,  at  a  set  limit  of  pressure,  a  minimum 
weight  of  powder  will  develop  the  greatest  velocity 
that  can  be  developed  at  that  pressure.  If  strips  of 
other  thicknesses  develop  practically  identical  veloci- 
ties and  pressures  for  the  same  pressure  limits,  it  will 
be  by  burning  greater  weights  of  powder.  Such  a 
powder  may  be  designated  a  maximum  powder,  for 
the  material  from  which  it  is  prepared  and  for  the  gun 
from  which  it  is  fired. 

Suppose,  then,  that  colloided  gun-cotton  of  nitra- 
tion N=  13.3  develops  in  a  given  gun  a  maximum 

value  V/P  = ,  what  will  be  the  effect  of  incor- 
porating into  such  powder  a  certain  quantity  of  nitro- 
glycerin,  or  of  metallic  nitrates  such  as  barium  and 
potassium  nitrates?  Assume  that  during  the  process 
of  colloiding  the  requisite  quantity  of  nitrates  be  uni- 
formly incorporated  throughout  the  substance  of  the 
pasty  mass,  which  is  subsequently  formed  into  strips, 
as  before.  For  this  material  we  shall  find  that  the 

maximum  powder  develops  a  value  of  V/P— 1 

2100 
as  against  — — •  for  the  pure  colloid,  a  gain  in  velocity 

imv\ 
of  300  ft.  sec.  for  a  given  pressure;  in  energy,  f ), 

of  about  30  per  cent, 


1 82  SMOKELESS  POWDER 

If,  in  lieu  of  nitrates,  we  incorporate  nitro-glycerin 
into  the  colloid,  we  will  obtain  a  pasty  mass  that  can 
be  worked  conveniently  into  the  form  of  rods  or 
cords,  whence  the  name  "  cordite,"  applied  to  one  of 
its  best  known  types.  Cordite,  as  used  in  England, 
consists  of 

Nitro-glycerin 58  parts 

Gun-cotton 37  parts 

Vaseline   5  parts 

Such  a  powder,  fired  under  the  above  conditions, 
develops  a  value  of  V/P  =  — —  approx. 

There  is  one  characteristic  of  powders,  such  as  the 
K  and  the  French  BN,  containing  nitrates,  to  which 
attention  is  to  be  directed.  The  nitrates  contained  in 
these  powders  exist  in  them  in  a  state  of  suspension; 
in  an  undissolved  state.  For  the  BN  the  microscope 
reveals  minute  crystalline  particles  uniformly  dissem- 
inated throughout  its  mass;  the  barium  nitrate  em- 
ployed in  the  K  powder  is  insoluble  in  the  colloiding 
agent,  acetone,  and  is  also  insoluble  in  the  colloid,  in 
which  it  is  held  in  a  state  of  suspension  and  of  uni- 
form distribution. 

In  the  case  of  the  nitro-glycerin  powders  it  is 
known  that  the  nitro-cellulose  is  not  in  true  solution 
in  the  nitro-glycerin.  In  this  connection  the  follow- 
ing quotation  from  an  authority  upon  nitro-glycerin 
powders,  Mr.  Hudson  Maxim,  may  be  cited: 

"  In  the  very  early  smokeless  powders,  especially 
those  made  of  compounds  of  soluble  pyroxylin  (gun- 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    183 

cotton)  and  nitro-glycerin,  it  was  supposed  that  the 
mtro-glycerin  actually  held  and  retained  the  pyroxy- 
lin in  solution,  but  it  has  since  been  learned  that  the 
nitro-glycerin  is  held  by  smokeless  powders,  whether 
made  from  high-  or  from  low-grade  gun-cottons,  in 
much  the  same  manner  as  water  is  held  by  a  sponge; 
in  fact,  the  pyroxylin  exists  in  smokeless  powders  in 
the  shape  of  a  very  minute  spongy  substance,  and  the 
nitro-glycerin  is  held  in  a  free  state  within  the  pores 
of  this  sponge." 

"  It  is  possible  even  with  powders  containing  as 
little  as  25  per  cent,  of  nitro-glycerin,  to  squeeze  out 
the  nitro-glycerin  in  a  pure  state  by  subjecting  a  piece 
of  this  powder  to  great  pressure  between  smooth 
steel  plates." 

The  quantity  of  nitro-carrier  (nitrate  or  nitro-sub- 
stitution  compound  other  than  nitro-cellulose)  consid- 
ered necessary  to  the  production  of  good  ballistic  re- 
sults, as  exemplified  in  certain  known  powders,  may 
be  tabulated  as  follows: 

TABLE   III 

Variety  of  Nitrn-rarrW  n^H  Per  ceot-  of  Nitro-carrier 

Powder  in  Given  Wt.  of  Powder 

Cordite Nitro-glycerin 58 

Maxim Nitro-glycerin 10  to  25 

BN Barium- and  Potassium  nitrates  211025 

K Barium  nitrate 14.25 

The  composition  and  ballistic  properties  of  the 
three  classes  of  explosives — pure  colloids,  colloids 
containing  metallic  nitrates,  and  colloids  containing 
nitro-glycerin — may  be  compared  as  follows; 


1 84 


SMOKELESS  POWDER 
TABLE   IV 


Pure  Colloid 

K 

BN 

Cordite 

Gun-cot- 

Gun-cot- "1 

Insol.  nitro- 

Nitro-gly- 

ton,         85.00 

ton  and 

cellulose,  38.67 

cerin,        58 

Soluble  ni- 

soluble     !  QA  . 

tro-cellu- 

nitro-cel-f84'25 

Soluble  nitro- 

Gun-cot- 

lose,       10.00 

lulose, 

cellulose,  33.23 

ton,           37 

Sod.  carb,  i.oo 

balanced  J 

Barium 

Vaseline,    5 

Solvent,  res- 

Barium 

nitrate,     18.74 



ins,  etc.,  4.00 

nitrate,       14.25 

100 

T^/-\f  o  cciii  m 

100.00 

Calc.  carb.,  1.50 

lUldr^olU  III 

nitrate,       4.54 

100.00 

Calc.  carb.,  3.  65 

Volatile,       1.29 

100.12 

TABLE  V 


Type 

Pure 
Colloid 

Metallic  Nitrate 

Metallic  Nitrate 

Nitro-glycerin 

Manner 

Solid  undis- 

Solid    undis- 

Undissolved 

of  incor- 

solved   parti- 

solved parti- 

particles 

poration 

cles,  uniform- 

cles, uniform- 

held in  sus- 

of oxy- 

ly distributed 

ly  distributed 

pension  like 

gen-ear- 

throughout 

throughout 

water  in 

ner 

colloid  ma- 

colloid ma- 

sponge 

trix 

trix 

V 

2IOO 

2400 

2400 

2400 

P 

15-19 

15 

15 

15 

Remembering  what  has  been  said  in  relation  to  the 
ballistic  performance  of  the  varieties  of  powders  cited, 
we  are  led  to  the  following  conclusion: 

That  minute  particles  of  an  oxygen-carrier  uniformly 
incorporated  into  a  nitro-colloid  and  held  in  suspension 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    1 8$ 

in  an  undissolved  state  throughout  the  body  of  the  latter, 
render  more  progressive  the  combustion  of  the  nitro- 
colloid  into  which  they  are  incorporated. 

For  convenience  of  reference  I  shall  refer  here- 
after to  the  oxygen-carrier  held  in  suspension  in  the 
colloid  as  the  accelerator.  Viewed  in  the  light  of  the 
principle  here  enunciated,  the  several  powders  we 
have  been  considering  are  all  similar  variants  of  the 
pure  colloid.  The  remark  of  the  compounder,  "  that 
a  little  nitro-glycerin  certainly  does  help  the  powder 
along,"  is  now  the  more  readily  comprehensible. 

The  methods  commonly  employed  for  co-ordina- 
ting natural  species  may  be  applied,  by  way  of  illus- 
tration, to  the  classification  of  the  various  types  of 
progressive  explosives,  to  establish  their  relations  to 
one  another,  and  to  indicate  the  lines  along  which 
advances  have  been  effected. 

We  shall  next  consider  how  the  accelerator  acts  to 
develop  increased  velocity  without  developing  in- 
creased pressure. 

i. — It  has  already  been  shown  how  it  is  possible 
with  powders  containing  as  little  as  25  per  cent,  of 
nitro-glycerin  to  squeeze  out  the  nitro-glycerin  in  a 
pure  state  by  subjecting  the  powder  to  great  pressure 
between  smooth  steel  plates. 

If  it  be  possible  to  extract  nitro-glycerin  by  appli- 
cation of  pressure  from  powder  in  which  it  is  incor- 
porated, then  there  will  be  a  tendency  to  flow  in  the 
direction  of  least  pressure  from  the  instant  of  ignition 
of  a  charge  to  that  of  its  complete  combustion.  This 
would  mean,  first,  flow  from  within  outwards  in  the 


1 86 


SMOKELESS  POWDER 


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THE  DEVELOPMENT  OF  SMOKELESS  POWDEK    1 87 

gun-chamber,  where  a  relatively  large  proportion  of 
the  nitre-glycerin  would  be  consumed;  second,  flow 
in  the  direction  of  the  windage,  where  the  quantity  of 
nitre-glycerin  consumed  would  also  be  relatively 
great.  Such  action  accounts  for  the  rapid  erosion  of 
the  surfaces  of  gun-chamber  and  rifled  bore  when 
powders  containing  nitro-glycerin  are  employed. 

2. — The  eminent  Russian  chemist,  Professor  D. 
Mendeleef,  developer  of  smokeless  powder  in  Russia, 
in  a  paper  upon  pyrocellulose  powder,  says: 

:<  The  chemical  homogeneity  of  pyrocollodion 
plays  an  important  part  in  its  combustion,  for  there 
are  many  reasons  for  believing  that  upon  the  com- 
bustion of  those  physically  but  not  chemically 
homogeneous  materials,  such  as  nitro-glycerin  pow- 
der (ballistite,  cordite,  etc.),  the  nitro-glycerin  is  de- 
composed first,  and  the  nitro-cellulose  subsequently 
in  a  different  layer  of  the  powder.  The  experiments 
of  Messrs.  T.  M.  and  P.  M.  Tcheltsov  at  the  Scientific 
and  Technical  Laboratory  show  that  for  a  given 
density  of  loading  the  composition  of  the  gases 
evolved  by  nitro-glycerin  powders  varies  according 
to  the  surface  area  of  the  grains  (thickness  of  strip), 
a  phenomenon  not  to  be  observed  in  the  combustion 
of  the  pyrocellulose  powders.  There  is  only  one  ex- 
planation for  this,  viz.,  that  the  nitro-glycerin,  which, 
possesses  the  higher  rate  of  combustion  (Berthelot), 
is  decomposed  sooner  than  the  nitro-cellulose  dis- 
solved in  it.  This  is  the  reason  why  nitro-glycerin 
powders  destroy  the  inner  surfaces  of  gun-chambers 
with  such  rapidity." 


1 88  SMOKELESS  POWDER 

We  conclude  from  the  above  that  the  nitro-glycerin 
incorporated  into  a  colloid  burns  more  rapidly  than 
the  nitro-cellulose  forming  the  colloid.  More  nitro- 
glycerin  is  consumed  with  one  part  of  the  charge  than 
with  another.  During  the  first  period  the  products 
of  combustion  evolved  in  chamber  and  bore  are 
largely  those  of  nitro-glycerin;  during  the  second, 
those  of  nitro-cellulose. 

Moreover,  as  both  materials  exist  in  an  uncom- 
bined  state,  although  in  one  of  intimate  admixture; 
as  both  decompose  wholly  into  gases,  while  each  con- 
tains sufficient  energy  to  continue  its  own  decompo- 
sition, once  that  decomposition  is  begun,  there  is  no 
reason  why  the  rates  of  the  two  decompositions 
should  be  equal;  it  would  rather  appear  that  each 
substance  should  decompose  at  the  rate  peculiar  to 
itself,  so  far  as  it  was  able,  under  existing  conditions 
of  heat  and  pressure,  to  effect  a  separation  of  its  sub- 
stance from  the  mixed  mass  of  the  powder. 

Conditions  point,  therefore,  to  there  being  two  in- 
tervals in  the  decomposition  of  the  charge,  during  one 
of  which  a  maximum  quantity  of  nitro-glycerin,  and, 
during  another,  a  maximum  quantity  of  nitro-cellu- 
lose is  burning. 

In  what  follows  it  is  not  intended  to  attempt  more 
than  to  indicate  the  mode  of  progressive  combustion 
as  implying  the  superimposition  of  maxima  and 
minima  of  effort.  This  may  be  represented  graphic- 
ally in  the  present  case  as  follows: 


THE  DEVELOPMENT  OF  SMOKELESS  POWDER    189 

NITRO-GLYCERIN  NITROCELLULOSE. 


The  result  of  the  combination  of  the  conditions 
here  indicated  would  be  the  imparting  of  a  double  im- 
pulse to  the  projectiles  due  to  the  successive  occur- 
rence of  two  maxima  of  acceleration.  Considered  as 
to  their  limit  of  possible  range,  the  successive  im- 
pulses may  occur  incrementally,  so  that  the  accelera- 
tor may  be  expressed  in  the  form 


where  p'  represents  the  pressure  due  at  any  instant  to 
the  combustion  of  the  nitro-glycerin;  />",  that  due  to 
the  nitro-cellulose. 

The  projectile  may  be  regarded  as  receiving  a  third 
impulse,  resulting  from  the  chemical  combination  of 
the  gases  evolved  by  the  nitro-glycerin  and  the  nitro- 
cellulose. According  to  the  researches  of  Messrs. 
Macnab  and  Ristori  (Proc.  Royal  Soc.,  vol.  LVI, 
p.  8),  the  decomposition  products  of  nitro-glycerin 
are 


CO2        CO      CH4       O 

57.6        —        —        2.7 


H 


N 
18.8 


H2O. 

20.7 


190  SMOKELESS  POWDER 

And  from  the  same  source  we  obtain  the  decomposi- 
tion products  of  nitro-cellulose  (N  =  13.3)  as 

CO2          CO        CA4       O        H  N         H2O 

29.27       38.52       0.24  0.86       13.6       16.3 

What  may  be  called  the  third  impulse  would  repre- 
sent the  combination  at  a  high  temperature  of  mul- 
tiples of  decomposition  products  developed  in  the 
ratios 

^FC02          CO       CH4      O        H         N       H20n 
l_57.6  2.7      —       18.8     20.8J 

.#[29.27     38.52     0.24  0.86     13.6     16.3] 

These  phases  may  be  indicated  graphically  as  fol- 
lows: 


COMBINATION  OF  PRODUCTS  OF 
COMBUSTION  OF  NITRO-GLYCFRIN 
NITRO-GLYCERIN  AND  NITRO-CELLULOSE  AND  NITRO-CELLULOSE 


Accelerated  colloids  of  K  and  BN  types  containing 
metallic  nitrates  are  next  to  be  considered.  We  may 
assume  that  the  nitro-colloid  into  which  minute  par- 
ticles of  a  nitro-carrier  of  this  type  are  cemented  itself 
burns  in  approximation  to  the  law  of  decomposition 
of  the  colloid.  This  state  of  affairs  is  similar  to, 


THE  DEVELOPMENT  OF  SMOKELESS  POtVDER    IQl 

though  not  identical  with,  the  preceding;  in  the 
former,  both  nitro-glycerin  and  nitro-cellulose  are 
able  to  effect  their  own  decomposition,  evolving 
gases  that  recombine;  in  the  latter,  the  nitro-cellulose 
alone  possesses  this  property,  the  metallic  nitrates 
surrendering  their  oxygen  through  the  effect  of  heat 
developed  during  decomposition  of  the  colloid.  The 
successive  reactions  may  be  represented  as  follows: 

UNION  OF  GASEOUS  DECOMPOSITION 
NITRO-CELLULOSE  PRODUCTS 


DECOMPOSITION  OF  BARIUM 
NITRATE 


Instead  of  three  maxima  of  effort  there  are  two 
maxima  and  one  minimum,  the  maxima  representing 
the  combustion  of  the  nitro-cellulose  and  the  subse- 
quent combination  of  the  gases  therefrom  with  the 
oxygen  of  the  barium  nitrate;  the  minimum,  the  ab- 
sorption of  heat  expended  in  decomposition  of  the 
barium  nitrate. 

A  comparison  of  the  diagrams  shows  that  the  proc- 
esses of  combustion  in  the  case  of  colloids  containing 
nitro-glycerin  and  of  those  containing  metallic  ni- 
trates are  similar.  Both  represent  aggregates  of 
work  resulting  from  successions  of  independent  de- 
compositions. For  such  powders  an  element  of  time 
enters  into  our  conception  of  chemical  action;  what 
the  ultimate  products  of  combustion  are  depends 
upon  the  order  of  occurrence  of  successive  evolutions 


I92  SMOKELESS  POWDER 

of  various  volumes  of  different  gases  at  high  tem- 
peratures.* 

The  base  of  the  projectile  is  subjected  to  a  series  of 
impulses  due  to  the  development  of  successive  waves 
of  pressure;  the  result  is  an  increased  initial  velocity 
for  a  given  developed  pressure,  the  acceleration  be- 
ing sustained  throughout  a  comparatively  longer 
period  of  time. 

Those  familiar  with  experimental  development  of 
ordnance  during  recent  years  remember  a  type  of 
multi-charge  gun  the  construction  of  which  seemed 
based  upon  a  favorable  combination  of  correct  prin- 
ciples, but  which  was  rejected  on  trial,  as  its  practical 
disadvantages  were  found  to  outweigh  by  far  its  ad- 
vantages. I  refer  to  the  Lyman-Haskell  multi-charge 
gun,  a  weapon  supplied  with  a  number  of  pockets  dis- 
tributed along  the  axis  of  the  bore.  In  each  pocket 
a  charge  of  powder  was  placed;  it  was  supposed  that 
the  projectile,  by  uncovering  successive  pockets  in  its 
flight,  would  cause  their  contents  to  ignite  and  thus 
furnish  successive  accelerating  impulses  to  increase 
its  velocity. 

From  what  has  been  already  said  in  relation  to  the 
principle  of  successive  combustion,  it  will  be  seen 
that  the  employment  of  charges  of  accelerated  pow- 
der, like  those  above  described,  in  a  gun  of  present- 
day  type,  represents  the  limiting  extension  of  the 
multi-charge  principle.  In  relation  to  their  succes- 
sive combustions,  the  nitro-glycerin  and  the  nitro- 

*See  extracts  from  paper  by  Prof.  Mendel6ef,  p.  33. 


THE  DErELOPMENT  OF  SMOKELESS  POWDER   193 

cellulose  may  be  considered  as  sub-charges,  con- 
tained in  independent  chambers  or  pockets,  or  dis- 
tributed throughout  a  very  large  number  of  small 
pockets. 

The  principle  already  stated,  as  established  by  the 
study  of  the  ballistic  action  of  accelerated  or  com- 
posite powders,  may  be  now  amplified  as  follows: 

Minute  particles  of  an  oxygen-carrier,  uniformly  in- 
corporated  into  a  nitro-colloid  and  held  in  suspension 
throughout  the  mass  of  the  colloid  in  an  undissolved 
state,  act  through  their  independent  combustion  in  such 
a  manner  as  to  render  more  progressive  the  combustion 
of  the  colloid  into  which  they  are  incorporated. 


INDEX 


PAGE 

Accelerator 185 

Acid,  nitric,  table  showing  action  and  results  of  mixtures  of . . .  83 

Nitrohydric 109 

Sulpho-nitrie,  table  showing  action  and  results  of  mix- 
tures of 87 

Acid  bath,  table  showing  composition  of,  in  relation  to  yield  of 

nitrogen  dioxide 132 

Alcohol,  absolute,  as  a  solvent 52 

Action  of,  in  facilitating  solution 43 

Alkalies,  action  of,  on  cellulose 46 

Ammonium  compounds  as  materials  for  explosives 108 

Ammonium  nitrate  in  smokeless  powders 122 

Attainment  of  maximum  propulsive  effect 169 

Ballistic  efficiencies   of   pure   colloids  and  compound  colloids 

containing  accelerators,  table  showing 167 

Ballistic  properties  and  composition  of  explosives,  table  show- 
ing   184,  186 

Ballistite 117 

Benzol  derivatives  as  materials  for  explosives 121 

Cellulose 5 

Action  of  alkaline  hydrates  on 46 

As  a  base  for  smokeless  powders 125 

Composition  of 57 

Conditions  governing  formulation  of 66 

Constitution  of 21 

Dinitrate  14 

Electrolytic  strain  in 50 

Hexanitrate  12 

195 


196  INDEX 

PAGE 

Cellulose  hydrate,  composition  of 57 

Hydration  of 45 

Incompletely  nitrated  92 

Molecule,  theory  of 37 

Nitrates *. 74 

Nitrates,  composition  of 11 

Nitrates,  volume  of  nitrogen  dioxide  disengaged  per  gram 

by  128 

Pentanitrate  13 

Structure  of 21,  59,  60,  61 

Structure  of  polymeric  forms  of 63,  64 

Tetranitrate 13 

Thiocarbonate   48 

Trinitrate  13 

Type 69,  70 

Cocoa  powder,  gases  evolved  by 101 

Cold,  action  of,  in  accelerating  solution 51 

Solubility  of  nitro-celluloses  in  the 43 

Solubility  of  njitro-hydrocellulose  in  the 41,  42 

Solubility  of  pyrocellulose  in  the 43 

Collodion  cotton 7 

Collodion-pyroxylin 7,  13 

Collodions 16 

Table  showing  effect  of  washing  and  pulping  on  viscosity 

of 151 

Colloid  161 

Colloidization  71 

Colloids,   accelerated 190 

Colloids,    compound,    containing   accelerators,    table    showing 

ballistic  efficiencies  of 167 

Pure,  table  showing  ballistic  efficiencies  of 167 

Combustion,  complete 173 

Of  grains 179 

Of  powder 110 

Complete  combustion 173 

Composite  powders 179 

Cordite 166 

Cotton,  friable 7 

Nitration  of 127 

Researches  upon  nitration  of 81 

Definitions 5 


INDEX  197 

PAGE 

Deterrents 165 

Dinitro- methane,  explosive  properties  of 112 

Ether  as  a  solvent 55 

Ether-alcohol  as  a  solvent 51,  55 

Experiments,  various 144 

Explosives,  ammonium  compounds  as  materials  for 108 

Benzol  derivatives  as  materials  for 121 

Hydrocarbons  as  materials  for 109 

Tables  showing  composition  and  ballistic  properties  of.  184,  186 

Friable  cottons 7,  16 

Gases,  calculating  volume  evolved 99 

Evolved  by  ballistite 117 

Evolved  by  black  powder 100 

Evolved  by  brown  powder 101 

Evolved  by  nitro-cellulose 102 

Evolved  by  nitroform 113 

Evolved  by  nitro-glycerin 101,  124 

Evolved  by  nitrohydric  acid 109 

Evolved  by  pentanitro-cellulose 102 

Evolved  by  pyrocollodion 105 

Evolved  by  pyroxylin 122 

Evolved  by  tetranitro-cellulose 103 

Evolved  by  trinitro-cellulose 102 

Gun-cotton  ..'...' 7,  12,  102 

Discovery  of . . 1 

Table  showing  effect  of  pulping  on 151 

Table  showing  effect  of  washing  on * 151 

Gun-cottons 16 

Hydration 75 

Hydrocarbons,  as  materials  for  explosives 109 

Hydrocellulose  0 

Amorphous 50 

Mercerization  47,  71 

Mononitro-methane,  explosive  properties  of 112 

Multi-charge  principle 192 

Nitration  5,  71 

Experiments  in 134,  140,  141 

Higher  limit  of  degree  of 91 

Of  cotton 127 

Of  cotton,  researches  upon 81 


1 98  INDEX 

PAGE 

Nitration,  table  showing  results  of,   for   different  periods  of 

time   137,  142,  145 

Temperature  in 35,  36 

Nitro-cellulose 5,  161 

Composition  of 94 

Decomposition-products  of 190 

Formula  of 94 

Gases  evolved  by 102 

Insoluble 5 

Of  high  nitration 5 

Of  low  nitration 5 

Of  mean  nitration 5 

Soluble ,       6 

Nitro-celluloses,  properties  of 95 

Solubility  of,  in  the  cold 43 

Nitroform,  explosive  properties  of 112 

Gases  evolved  by 113 

Nitrogen  dioxide,  table  showing  yield  of,  in  relation  to  com- 
position of  acid  bath 132 

Volume  disengaged  per  gram  of  cellulose  nitrates 128 

Nitre-glycerin    116 

Decomposition-products  of 189 

Gases  evolved  by 101 

Gas  volume  developed  by 124 

In  smokeless  powders' 182 

Nitro-hydrocellulose  6 

Insoluble 7 

Of  high  nitration 6 

Of  mean  nitration 6 

Of  low  nitration 6 

Soluble 7 

Solubility  at  freezing  temperature 41,  42 

Solutions 38 

Nitro-hydrocelluloses,  constitution  of 34 

Nitro-mannite 116,  118 

Nomenclature 4 

Oxygen-carriers   32 

Pentanitro-cellulose,  gases  evolved  by 102 

Polymerization    71 

Powder,  black,  gases  evolved  by 100 

Cocoa  (brown),  gases  evolved  by 101 


INDEX  199 

FAGK 

Powder,  pyroxylin 125 

Smokeless,  development  of 156 

Smokeless,  origin  of 1 

Smokeless,  ammonium  nitrate  in 122 

Smokeless,  cellulose  as  a  base  for 125 

Smokeless,  nitro-glycerin  in 182 

Smokeless,  pyrocellulose  as  a  base  for 175 

Smokeless,  pyrocollodion   as  a  base  for 97,  125 

Powders,  colloid 28 

Composite  179 

Table  showing  qualities  of 168 

Table  showing  quantity  of  nitro- carriers  in  certain 183 

Propulsive  effect,  attainment  of  maximum 169 

Pyrocellulose    7 

Adaptation  for  smokeless  powders 175 

Solubility  in  the  cold 43 

Pyrocollodion  97 

As  a  base  for  smokeless  powders 125 

Gases  evolved  by 105 

Smokeless  powders  from 97 

Pyroxylin   7 

Gas  volume  developed  by 122 

Powder » 125 

Pyroxylin  and  nitro-naphthalin 122 

Pyroxylin  and  picric  acid 122 

Smokeless  powder,  development  of 156 

Origin  of 1 

Smokeless  powders,  ammonium  nitrate  in 122 

Cellulose  as  a  base  for 125 

Nitro-glycerin  in 182 

Pyrocellulose  as  ai  base  for 175 

Pyrocollodion  as  a  base  for. 97,  125 

Solubility,  temperature  in  relation  to 41,  44 

Solution,  action  of  cold  in  accelerating 51 

Table  showing  action  of  nitric  acid  mixtures,  and  results 83 

Showing  action  of  snlpho-nitrio  acid  and  mixtures,  and 

results 87 

Showing  ballistic  efficiencies  of  pure  colloids   and   com- 
pound colloids  containing  accelerators 167 

Showing   composition  and  ballistic  properties   of  explo- 
sives   184,  186 


200  INDEX 

PAGE 

Table  showing  composition  of  acid  bath  in  relation  to  yield 

of  nitrogen  dioxide 132 

Showing  effect  of  temperature  during  dipping  and  reac- 
tion     149 

Showing  effect  of  pulping  on  gun-cotton 151 

Showing  effect  of  washing  on  gun-cotton 151 

Showing  effect  of  washing  and  pulping  on  the  viscosity  of 

collodions    151 

Showing  qualities  of  powders 168 

Showing  quantity  of  nitro-carrier  in  certain  powders 183 

Showing  results  of  nitration  for  different  periods  of  time. 

137,  142,  145 

Temperature,  in  nitration 35,  36 

In  relation  to  solubility 41,  44 

Table  showing  effect  of,  during  dipping  and  reaction 149 

Tetranitro-cellulose,  gases  evolved  by 103 

Tetranitro-methane,  explosive  properties  of 113 

Theory  of  cellulose  molecule 37 

Trinitro- methane,  explosive  properties  of 112 

Viscosity 27 

Of  collodions,  table  showing  effect  of  washing  and  pulping 
on  .  .   151 


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Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  00 

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"      Law  of  Field  Operation  in  Engineering,  etc 8vo,  5  00 

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